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Introduction to Pneumatic Control Systems

Introduction to Pneumatic Control Systems

Video: 
March 24, 2010 - 11:00am

Beginning on March 24, we will be offering the first of four Webinars on pneumatic control systems.  The following sessions will be conducted in April, May and June.  The topics covered will include basic air supply systems, pneumatic terminology, thermostats, receiver/controllers, actuators, and more.

Who should attend:  Maintenance people at the user level and service technicians

Speaker(s): 

John Graham is a senior engineer at Industrial Controls and has close to 30 years experience in the industry. In that time, he has worked with mechanical contractors and industrial and commercial customers selecting discrete components and designing HVAC and industrial solutions. Pneumatics and combustion are two of his many areas of expertise. John did his undergraduate work at the Milwaukee School of Engineering.

Carl Johnsen is a Commercial Distributor Rep for Honeywell and has been with them for 37 years.  Carl was previously a New Construction Technician, Service & Installation Manager, and a National Accounts Manager.  Carl graduated from the University of Illinois with a BS degree in Industrial Education.  Carl has his FAA - Airframe & PowerPlant Mechanic License, FCC - 1st Class License with Ship Radar Endorsement, and is a Certified Energy Manager.

Transcript: 

David:

Okay, let's get started. My name is David and I'm marketing manager for Industrial Controls and today we are going to have a webinar about pneumatic control systems. The presentation is going to take about forty-five minutes. We're going to hear from two experts. At the end of the presentation, we are going to take some time and we are going to answer your questions. There are two ways that you can ask questions. One way is if you look in your screen there is a chat box where you can actually a question and I can read the questions for you and our panelists will answer them. Also, if you're on the phone line and are not using a microphone, you can raise your hand using the interface and we can call on you and you can ask your question. So we are going to wait until we are done with the presentation before we do those though.

I'd like to introduce John . He is a senior engineer at Industrial Controls and has close to 30 years experience in the industry. In that time, he has worked with mechanical contractors and industrial and commercial customers selecting discrete components and designing HVAC and industrial solutions. He has pneumatic and combustion experience in many areas of expertise in those. He did his undergraduate work at the Milwaukee School of Engineering.

I'd also like to introduce Carl from Honeywell. He is a Commercial Distributor Rep and has been with them for 37 years. He was previously a New Construction Technician, Service & Installation Manager, and a National Accounts Manager. Carl graduated from the University of Illinois with a BS degree in Industrial Education. Carl has his FAA - Airframe & Power Plant Mechanic License, FCC - 1st Class License with Ship Radar Endorsement, and is a Certified Energy Manager. So at this time I'd like to pass it to John.

John :

On behalf on your friends at Industrial Controls, we'd like to welcome you to the first in the series of pneumatics seminars aimed at demystifying pneumatic controls. Today's seminar will be close to an hour and Carl and I are going to kind of trade-off as we go to keep it conversational. Today's focus is going to be somewhat introductory really. We are going to begin with the air supply which is the motive force for pretty much any pneumatic system. We have dates for the next three sessions and they are April 21st and we are going to be talking about thermostats and controllers. Devices, relays, actuators and such and last of all June 16, the applications so if you forget the dates just keep in mind it's going to be the third Wednesday of the next three months. That's probably the easiest way to remember that. Although the first pneumatic control system was patented by Warren 115 years ago they are still quite viable. When the benefits of pneumatics are combined with today's DDC systems, you can leverage quite a bit. So at that, we are going to dig in and I'm going to pass it along to Carl.

Carl:

John thanks for the introduction and I'm going to try to move forward here so bare with us. We are going to be advancing the next slide so hopefully people can see that. We do have a student computer over on the other side. Pneumatic control fundamentals part one- hopefully somebody can touch base with Mark on that as far as listening to him on the telephone. For our objectives for this morning we are going to be talking about major components of pneumatic controls and we are going to be looking at an understanding pneumatic terminology. I think with any new type of thing that you are trying to learn just getting the basic terminology down and once you understand the terminology and then you can move forward with that. So that is what our focus is for today. Also, from a service standpoint and we will start with people in the field with existing installations and not really as a new or going at it from an application engineering standpoint. We can answer some questions in regards to that but the focus is our service repair and troubleshooting. So today we are going to be looking at the main air compressor and the mechanical rooms. We are going to be talking about the dryers that are going to be drying in the air and looking at the pressure reducing valves that take that air pressure from the compressor and send it out to the rest of the building. And as they are wrapping it up, were going to talk about pneumatics in the marketplace and look at where pneumatics has come from and where pneumatics are going in the future.

So were going to advance the next slide and hopefully that's coming up on everybody's computer. Everybody should see the overview as far as seeing the compressor, refrigerated air dryers, a picture of that, and also a picture of filter stations and PRVs and also going out to the pneumatic thermostats. So I think a lot of times we look at pneumatic air supply sources and kind of skipped over it. Everybody wants to start learning about what the thermostats do and what the controllers do and we really want to focus today on the mechanical rooms and what goes on in that mechanical room because it's a really, really important part of any of the pneumatic control systems in any building. So we want to look at these individual items. Make sure they are fully understood and also look at the risk if we don't maintain them or if they are not look at and repaired quickly. We will be going through those topics as well. So we want to be able to supply a clean air. We want to make sure that it's dry and oil free and make sure that it has an adequate volume. And also, we'll talk about the reliability and also we put on ads and look at different things as far as going through and walking through and doing job surveys which John and I both do on a pretty regular basis. So were going to be able to hopefully impart some of what we do and maybe you can also share during your question session what questions you might have and what you do.

John:

Sure, so what were going to do is start off with the compressor and that's obviously our motive source for the system and when we think of compressor we think about it as a large module, a unit if you will, but it's really broken down or can be into another couple of components. The one depicted on this slide is called a simplex meaning it's only got one pump, one motor. Some compressors for redundancy will have multiple motors and pumps on one receiver. The receiver itself being just the tank, hopefully you can see the mouse there. The air comes in as you would guess through the filters at the top of the compressor. Goes through a set of reed valves and on every downward stroke of the piston we draw air in. As the crank continues to turn, we push the piston up, another set of reed valves open and allow air to pass into the receiver. The cycle continues until the pressure switch is satisfied and that's typically done at 80 to 100 psi. The reason we do that is to store air at high pressure so that the receiver size isn't physically so large. The problem points quite often are limited to obviously a problem with the motor, the belt, the compressor. It can be a number of things really but we take air at high pressure, we pass it through the refrigerated air dryer, which we will talk about in a moment, through the regulator and out to the system.

The compressor typically will run when properly size at about a third of the time meaning the duty cycle of runtime if it's on for five minutes it should be off for ten and that's done so that we extend compressor life. The types of compressors typically like depicted here would be the reciprocating type where you can actually see a piston moving if you were to take the head off of course. Or a rotary type or a turbine type and another important thing to consider with compressors that are designed for comfort applications as opposed to pneumatic power tools and the type of stuff that you see at most Home Depot stores and such is that these compressors are designed to turn very slowly so that we don't take a lot of oil out of the crank case and vaporize it past the rings of the compressor and push it down into the receiver. So the lower the crank speed the longer the life and the less aerosols as they're called pass through the compressor and into the system to be later extracted.

There is a tank range shown on the tank because obviously a natural byproduct of compressing the air is adding heat. That heated high pressure air comes into the cool receiver and you'll get a lot of condensate that needs to be removed there. So the automatic train is there to do that. It can be float operated meaning that you'll see a float chamber with a valve and a needle and as the float becomes buoyant because of the water elevating in that chamber it will discharge to a floor drain nearby. Some actually use solenoid valve and a timer. The timer is set for a certain on and off duration and based on just an imperial setting of those on and off times we arrive at some suitable amount of training. Again, that discharge to the floor drain. It's a pretty simple device really but it can be a neglected only because it's mechanical and it's running 24/7 and it does require maintenance.

Carl:

John, as far as the tank itself as far as you and I have been talking about what are the results what happens when it auto drain is not working properly?

John:

Well, you'll find first of all that the cycle time will change because some of the internal volume of the tank is consumed by water. Ultimately, at some point where that water becomes so high that it starts to come into the downstream components. We'll have a serious issue. So the auto drain itself should be looked at as sequencer should be really on a daily basis. We'd be looking for the drain line going to the floor drain or local drain to be wet of course because it's going to be operating all the time and just looking for compressed air pressures on the receiver, listening for sounds, smelling. If you've got belts that are burning or slipping, the motor might hesitate to start the pump so those kinds of individual checks are really prudent on a daily basis.

Carl:

Yeah, I think the compressor itself like we talked about earlier on it’s so important to make sure that you have this clean, dry oil free air. Don't take it for granted. The air that is coming out of this compressor is heating a lot of very expensive pieces of equipment throughout the whole building. So any of these people who were on the line today, if you're a facility engineer, to make sure that these things like John was saying are done on a daily basis because the cost of not doing these checks and doing maintenance and/or replacing this compressor if it goes bad with something that's not as quality is that you could be feeding water or oil into all these very expensive pieces of pneumatic equipment, thermostat, and controllers.

We are going to move on now to the refrigerated air dryer which is the section here and even though in our section we don't have a drain coming off the refrigerated air dryer there is still a drain that’s there. In general, the air dryer cools this tank an air that's coming off of that big compressor and tank. It's there to remove the moisture that's coming through that air line. Then to be able to do that, how do you check it? Well, you're going to be able to look at the drain again similar to what John was talking about for the compressor and to make sure that there is a drain and it is having moisture coming down in general so again do that on a daily basis. Then also the discharge of this refrigerated air dryer should have the piping temperature around that 38° to 40° so somebody can take their hand or you can just feel it or take an infrared thermometer and check to see what the temperature is on that discharge to know that it's cool and it is working. And also in this particular case we have a brand here, Hankinson, which is a pretty popular brand name and a Hankinson you're going to have a power on light that is going to be working and you should be checking that. And also there will be a light on this Hankinson and perhaps other brands as well that would have high temperature warning light saying that there is a problem inside.

This is just basically like a window air conditioner that's cooling down the air and cooling it down so it drags and pulls moisture out of the air and brings it to the drain. Now the maintenance part of this is fairly simple. It's cleaning the coils on a regular basis making sure that they have a free flow of air across them so it can do its job and making sure that the drain line is open, it's not clogged up with any dirt or dust and those kinds of things going to the drain. One of the comments that we get, John and I have talked about this a couple of times as far as what happens if this air line is actually being run outside? You might have rooftop units that require pneumatic air and so right now we are cooling this air down to this 38° to 40° and therefore removing the moisture of that. But if you actually run this air line outside you could have -10° or at least we do here in Milwaukee. If you have that cold air, you still are going to have moisture even though it's cooled down to 30° or 40°, you're still going to have moisture in the air and that -10° air could actually block the air lines going on the roof. So you have to be very careful and cautious in one of the solutions to doing that in addition to perhaps the refrigerated air dryer is to use an industrial type desiccant dryer which actually pull more moisture out of it and really drop and take moisture out so you can run those air lines on the roof and not experience any freezing conditions.

So one of the last pieces I want to mention is that some people don't think about it is that that compressor and the tank actually is the first stage of taking and drying the air. As the air moisture that's in the mechanical room, it’s there, yes, you have moisture there but what happens is when you compress that air the compressed air in the tank can't hold the moisture and it drops down to the bottom of the tank. And therefore pumping it up to 80 to 100 pounds actually starts the first part of that air drying and that's when moisture comes down and the over drain is so important.

John:

So it's really very easy to forget this type of equipment because it's quite often in a part of the building that doesn't get visited often but its emphasis can't be overstated. As a matter of testing from time to time to prove that this equipment is working one can actually take any branch air line and use a white piece of cloth perhaps or something fiber to allow a certain amount of air to pass and look for spots that might be oily. Or you might be able to even see air if you look at the free end of a piece of poly tubing. These kinds of things are indications that you probably should spend some time in the equipment room looking at the dryer, the filters, the compressor, and those types of things. The filters quite often that are out in the system that aren't depicted on the slide but you will commonly find that branch air from the regulator that goes into serving the entire building main will be further subdivided. It will serve commonly many pieces of control equipment. There will often times small filters aligned with the receiver controller, switching relays, the kinds of things we'll talk about later. Those filters will change color when they get oily and if you just do a spot check on that periodically. Look for color changes there. That can be an indication that those varied plank aerosols are making it through the supply system and ending up at the final control devices. Again, as Carl had said before what we are looking at is a very small part of the system but it has a great influence on the quality of the entire building control as well as the cost of maintenance and ownership. With that air clean and dry particulate free again, we are going to have much longer life at the final control devices.

And we will learn this later but the thermostats and a lot of relays and such have very small orifices that can be really quickly fouled with just fine particles or oil. So again, can't be overstated, there are means to clean systems like this if they've become contaminated. They typically involve breaking the system down into pieces, isolating, and flushing. There's products from Nu-Calgon for example that allow an injection of a solvent into the air stream typically after all your final devices have been removed from the air lines. We don't want to flush the dirt through these fine orifices within thermostats and such. That's something I've covered in their product literature but it should systems get out of hand there is some hope. You don't have to open walls up and tear piping out. It can be flushed in place but again we have to look at that building per building basis depending again on how fouled it is and how the whole system has been put together.

Carl:

We’ll just advance the slides now and we're going to take a little bit stronger look at and a more detailed look at this pressure reducing valves so bare with me as I advance the slide. Here we go. Hopefully the slides are coming up and you should be seeing a top called a single pressure reducing valve or PRV. So the main air that's coming in from the air dryer from the tank, this is the air dryer and there is a tank pressure, as John was saying 80 to 100 pounds, that's just in general. You'll probably find the PSIs for the tank pressures in different locations all over the map. But the pressure reducing valve has an addition to the PRV. It has this self micron filter and I'm trying to bring up my pointer so the air is coming in this direction and we have a glass bowl that can be seen here and see any accumulation of water and any accumulation of dirt or oil. There is also a drain at the bottom to be able to take any of those moistures or oils out of that glass globe.

In addition, we have gauges so on this size of the looking here on the left side of the PRV is going to be your tank air pressure and then coming through the PRV on the output of the PRV is going to be the gauge on the right hand side. So the left hand side gauge is the tank air pressure that 80 to 100 pounds and going to the right hand side of the PRV is the reduction going from tank air pressure then down anywhere between 18 to 25 pounds depending upon the manufacture and that particular building. And then the output of that PRV going out onto the right hand side is labeled M for main air line. That is the main air and that’s the acronym for M for the main air going out of the rest of the building.

Typically you might see a pressure relief valve on there from time to time. It is a small pop safety valve like you would see on a compressor or receiver tank but set to a much lower pressure and that is there to protect the instruments and the system should the regulator fail or should someone attempt to adjust it beyond its limit.

We are now going to move the sides forward and take a look at a dual pressure PRV and we are not going to get into how these are used right now but just in general we are going to introduce that going out of the main airline for the PRV's can be actually two different pressures, one for day and one for night and one for summer and one for winter and this is just one of the different setups that can be used that we have again the compressor air coming in on the left-hand side where my arrow is for my mouse, coming through tank air pressure on the left hand gauge and the right hand gauge is the output main air pressure. The main airline goes out here as it is going out to the building and this is labeled D or N in this particular case or could be Summer Winter but depending on the thermostats of the building, it could actually be switching for air pressures to be able to do a day set point or a night set point based upon the air pressure that is going out to the buildings.

In addition, towards the top, this is a time clock that is switching an electric to pneumatic relay that is actually forcing and moving this air pressure into the dual PRV to allow to those two different pressures. This electric to pneumatic relay is actually turned on and turned off in this case by time clock; it could be done by automation system, manual switches for the summer or the winter. So a lot of different ways that that could be set up to operate. And it is important to note that when we are talking about a duel pressure main, we are only going to switch between day and night or summer and winter or heating or cooling. It is not a system that can actually do a day/night and a cool. We will learn later what the thermostats and other devices that this air supply serves.

 

Building on that thought a bit, the next slide, you will see a brief table that further clarifies what we were just talking about, what the dual pressure means. On the left hand side we will see a number of brands of pneumatic components, Honeywell,, Siemens’ and so on and with these devices there are some typical pressures that you will see, so in other words, looking at Honeywell as an example, they will typically run a 13 pound day pressure and a 18 pound night pressure and the only difference is the thermostats have essentially two thermostats within them, there is a day and a night and all you have is similar control devices within each but you just steady your set point.

So example if you want a day setting of 68 and a night setting of 58, there are two identical stats within but the pressure is what indexes which thermostat into action, if that makes sense. Carrying along with a similar theme, Honeywell makes thermostats that give essentially a direct acting output or a reverse acting output based on the pressure of on the main and by that it is heating or cooling and some of these for example are not adjustable, some are. The Honeywell’s are designed to switch at fixed pressure at 13 and 18. The’s are adjustable anywhere from the range of 15 to 20. The Siemens’, like the 192 series are adjustable, the Barber Coleman TK’s are not, the Robert Shaw’s are.

So it is important when you select the replacement thermostat that if you are not going like for like, that you consider the pressure settings and where they are not adjustable, you have to take great caution. You also will see on the that it is a little bit different than the other in terms of the summer/winter operations, so just a word of caution that when you ask for a thermostat, day, night, summer, winter, just pay particular attention to that.

John:

We are really going to talk about the air supplies for larger buildings and so one of the things that we have seen and we want to review this morning is that these tank airlines that have high pressures, actually instead of having high pressure reducing valve in the mechanical room and just a single one for the entire building, we might actually have what they call a rise in high rise building, where that tank air pressure is going up at 80 to 100 pounds and going into each of the mechanical rooms, one might be on the 5th floor, one might be on the 10th floor, one might be on the 15th floor and then each of those mechanical rooms, then each of those mechanical rooms would have their own individual pressure reducing valve. These are pretty typical as far as seen in high rise buildings, so the larger air supplies would be run in half inch and/or ¾ inch pipes to be able to have the volume that is needed. In addition, the other layout would be more horizontal in nature for the building and that is if you have a wing for a hospital or a school, you can kind of picture the same thing having the high pressure ¾ inch pressure in the tank running down the hallway of the school and then going into the mechanical wing of that particular wing of the school and then again the PRV being in each mechanical room.

 

We are going to talk a little bit about trouble shooting.

Carl:

In terms of troubleshooting we typically look for the symptom of the problem first. Are you having an issue with controls on a certain air handling unit, where we cannot achieve, for example, a full economizer open damper, if we cannot achieve the pressure that we need at the equipment being served, that might be a symptom. If you walk into a building and every one of the zones are in full heat, know that the heating valves are typically to fail open that might be a symptom of a problem. So these kinds of things, a building, owner complaint, comfort issues, might tempt you to look at the instrumentation first whereby you hopefully will see that your pressures on your main are low and then you can go back to your equipment room, or as Carl had said, the local point of pressure regulation and look there. So if you find that the pressure is low at an air handling unit, you go back to the equipment room, check there at the regulator, is the pressure within expect there? If it is, we probably have a leak somewhere between the regulator and the equipment room and air handling unit, it becomes more of a logical process to break it down and help find out where that problem might be.

And fortunately air makes a great deal of noise when it leaks, at least for a larger sized leak, you can use your intuition to kind of listen for it. If you find that the pressure at the regulator is low, you might ask yourself if we are flowing too much, is the regulator miss set; is the air on the line side, the tank side of the regulator where it should be? That might point to an issue with a compressor itself, which may be nearby or faraway or perhaps there is a drain that is hanging, anything that doesn’t allow the system to maintain the pressure would obviously be a point of concern and something you should look into. There is ultrasonic leak detectors that are available to help you find smaller leaks, but sometimes the easiest thing to do is to use a pressure gauge and systematically isolate portions of the system until you restore pressure where it should be and not to mention obviously you should see run time differences. This is probably another real obvious indicator if the compressor is running all of the time, you know the air is going somewhere; it is costing a lot of energy, not only for compressed air but in terms of building comfort and such.

John :

I think that is a real good point John, as far as I think both of our experiences, again doing those job surveys, listening as we are walking through and doing the job surveys, listening to that compressor like you said earlier, making sure that compressor is running about %33 of the time ideally and not constantly running. If It is running a lot or that 1/3rd on or that 2/3rd off gets to be opposite with 1/3rd off and 2/3rd on, it would be saying that there is a leak somewhere and let’s take a look see what is going on and something that is not so easy to track down in some cases but it is the things you go out and look for.

Mass control systems. Really why, what is the background on some of these things that people have been talking about, pneumatic control system, why should you want to have one and in general I think that you will hear that pneumatic error and pneumatic controls are what we call inherently modulating and there are couple sides to this that John will go over here in a just a minute showing where this modulation is coming. It is not just on or off control. We actually have air pressure that that can actually do modulation from anywhere from full off to full open and anywhere and in between. I think that everybody that still says that pneumatic controls continue to be around a long time and to you keep hearing about the pneumatic controls going absolute, I think that is been going on since the 50s when everyone thought that electric or electronic controls where going to take over the world and pneumatics were still around. You still see a very, very, very large installed base of pneumatic controls at schools, universities and office buildings.

It is relatively easy to change when you are doing remodeling to add or move a pneumatic control or pneumatic thermostat so it is still going to be around. I think overall it is still less expensive than variable air volume per room or space control that you do a pneumatic AV as compared to doing electronic direct digital controls. It is still less expensive to do that especially in the last bullet point here saying where we have this existing pneumatic compressor, that is one of the larger capital investments on any job and to be able to know that it is already there and if you have a small change or a small add to the building, then hopefully the existing air compressor can be used and you do not have to incur additional costs for that that is certainly going to be around for a long time.

Carl:

I think some of the beauty is in its simplicity. It is easily understood by many who dive in and find that they can see things happening and such. What I would like to talk about it about something that Carl had mentioned in this slide. There is a discussion of inherently modulating and I want to expand on that. If you picture this slide with a wall-mounted thermostat and this could be any 2-position on/off thermostat, I picture in my mind like Honeywell T807F. It is just a set of contacts that would transfer on a fall in temperature that would command the valve to open and when the valve opens it would deliver full capacity heat to that zone. Now by that I mean, when you look at the original architect for a building, he is going to do a heat balance in every zone.

So let’s picture a corner office with a lot glass. There is going to be convection heat, there might be some air delivered through ceiling diffusers and such but at any rate he is going to select the appropriate amount of radiation and the operating steam pressure for designed conditions, which in Wisconsin is going to be 10 below or 20 below. So on a mild day when that thermostat calls for heat, the valve will open and deliver full designed capacity heat. The temperature will rise in the space and even with an anticipator on the thermostat, the temperature might exceed a point of comfort by a little bit, the stat opens, valve closes, temperature falls, temperature continues to fall and the valve reopens. You can kind of imagine that cycle continuing on and on so we are essentially blasting that space with a lot of heat, allowing it to cool and while in some places where the isn’t a creature comfort issue that is acceptable, in other conditions it is not. So that is typically your 2-position simple approach to temperature control.

If we look at the next slide we talk about inherent modulation. Pneumatic controls are inherently modulating, so we will explain that later what the thermostats, actuators and valves, but accept for now that the valve here that is shown on this hot water supply, it could be steam, it could be hot water, is going to open incrementally with changes in pressure on the diaphragm or from the branch of the thermostat. So in this case we saw a thermostat on a prior slide. This is the output line of the thermostat, it is called a branch. Carl had mentioned before the air supply is called the main, this is the branch. The branch pressure is delivered via poly or copper tube down to the valve and in most cases heating valves are selected to be normally open and they typically have a very low spring range, so as the temperature in the zone falls, the branch pressure falls and the valve begins to open just a little bit, admitting just a small amount of hot water through the convector or small amount of steam through the convector. As the temperature falls further and further from the desired set point, the valve opens more and more. So we have got the ability to add just a small amount of heat to that zone as opposed to design condition capacity. It gives you better comfort and in the electronic world, it is relatively difficult to do this. It’s not, I should say, difficult, but expensive. If we think about a 2-position electric zone valve, it is very inexpensive. If we picture a small electronically controlled ball valve, it is far more. The beauty of pneumatics, first of all in the case of the valve, is that it is very simple, it is very simple to maintain and troubleshoot but again it is inherently modulating. Very simple device. So again, the further from set point we are, the greater the corrective action, the greater the heat we add to that zone.

John :

The pull on/pull off that you are talking about certainly is not to make people comfortable is it?

Carl:

And costs money too in terms of the cycling and temperature.

John :

Here is what is going on in the market place and John and I just wanted to chat on these things and then do a little bit of a review. Certainly there are trends in the market place for let’s say taking an air handling unit and making that with direct digital electronic controls but leaving the zones pneumatic because the cost again of having pneumatic number stats is relatively inexpensive but to retrofit buildings, a lot of focusing on where the big recovery of the money would be for the initial first cost would be at the air handling units but leaving the zones as is. Is that you’re feeling as well John?

Carl:

Sure and one of the benefits is when you do add the DDC to pneumatics, you leverage the best of both worlds because as talked on a prior slide, the valves are very simple, very inexpensive and the direct digital controls oftentimes offers an electro pneumatic transducer, which will take the air supply and essentially modulate it to attain control of the valves. The other beauty of this, is quite often larger systems have very, very large valve and to get the force required to operate those valves, you have very large pneumatic actuators. They are very simple. We can develop a great amount of trust to operate the valves stem, very simply with a large diaphragm and large spring. So doing that electronically we require a very large motor typically, so those final control devices, if they are in good shape, are left alone and then we just take over control over them with the DDC system. So we leverage the simplicity on that end with the great power of today’s DDC’s systems.

John :

As you are talking about it John, it also occurs to me from a repair and service standpoint, those pneumatic operator has been around for so long and to repair one normally is just a rubber bladder, isn’t it?

Carl:

A diaphragm, yes, and the’s and Honeywell’s, those parts are still available even though the actuators themselves have been long obsolete, the springs are available, diaphragms are on the right model number to begin with and that you of course do it safely because when you pull the top off there is a big spring waiting for you, so that has to be done according to manufacturer’s instructions, but they are very maintainable.

John :

The third bullet item on the slide talks about explosion proof and gets into some of the industrial areas where they cannot have any of the devices, electric thermostats and those kind of things, having any kind of electricity or create perhaps the potential for a spark, so you will see and hear the word explosion proof as how pneumatics can be applied in an industrial marketplace and know that inherently that pneumatics are explosion proof and have a distinct advantage on over electric or electronic controls.

Carl:

Hugely less expensive and the systems are open, which to the end user means a lot. We do not need anything special to program use. Obviously there are little instruments that are needed to calibrate and service, but they are open and readily available. Thermostats from one manufacturer to another as long as you are careful about how you select them. There are a lot of options and I see the offers, a lot of these from stock. A lot of choice.

John :

Let’s do a wrap-up summary here and hear what we reviewed today. We talked about the major components of pneumatic control systems, being the compressors, the air dryers and the PRV’s.

 

 

Carl:

We reviewed some basics and understand that we are going to develop the other end of the system that we haven’t talked about much here later in the next three sessions. So if some of this is a little fuzzy, that is to be expected. We are really trying to focus more on the air supply.

John :

We talked about the air compressors and the dryers and the actually reducing valves and then we talked about in general where the pneumatics are in marketplaces, certainly are going ways. Everybody talks about the demise of the pneumatic systems. Those are going to be out there for a long period of time. So with that are there any questions online, David, if you want to try and look at the-

David:

Actually we did receive some chat questions during the presentation. I am going to go ahead and read those. While we go ahead and do that, we just want to give everybody else a chance to put some more questions in it, if you want to do that and again if you have a phone connection, you can raise your hand and we can call you as well. First question is from Jose. He asks, how often should the compressor oil be replaced and how should the air filters be replaced?

John :

Well. As supposed to in automobile where actually using the oil in the cylinders, that oil will become foul very quickly and that’s why we change the oil every 307,500 miles. In this case we are taking fresh air and there is some particular that will make it pass the filters which will eventually follow the oil. It’s primarily important to make sure that the level is up to where it belongs. I would suggest changing that probably every 6 months to be safe. Of course that’s the life bud of the system if lubricity break downs or there is a particular that will become abrasive to your journals on the crank, it will damage the bearings and it will score the pistol of the bore and shorten the life of the rings. So we don’t want those abrasives in there, best to drain it. And in filters, in terms of filters that’s a very good question because some compressors actually will take as supposed to a small sponge type, they will have a very large element. The larger the element, the longer the life typically. I would look more at visual build up on the external foam filter and may be, probably you got something.

Carl:

I was thinking as you were saying Jay, to be 100 percent also one of the things to look at would be look and try to document your particular building. To look at installations and operating manuals, to be able to now easily you can go online. Now it will on the internet, the last number of years to be able to download, if you don’t have manuals there, but certainly the document, your particular brand of compressor, your particular model number and look at the manufacturer’s recommendations for the amount of time that you should wait between changing oil and like Jay was saying, by looking at the air filters.

David:

Okay. Gary is raising his hands and I am going to give him the audio control. Gary, are you on the line? Hi Gary! Good morning Gary! We are having some trouble hearing. We will move on to the next. We have a text question from Mark. How is the pressures change between day and night, manually or automatically?

John :

Day and night, it’s typically done at the time clock or it can be done at the command of the building automation system and may be your question is more and how it’s done. That can be done as to fix it on to the slide with an electro pneumatic valve. There are other systems that will have literally two regulators. One day regulator, one night regulator. And then there is a large three way valve that simply selects the output of the appropriate regulator based on the time clock or the DDC system. So hopefully that answers your questions. So the pressure will oil B while we wanted to be based on the command from the clock or the DDC system.

Carl:

Yeah. It’s just I like to add some of that what we are talking about. It could be possibly manually change so that you will see Elasco systems where the custodian is at 5:00 in the morning and he throws the manual pneumatic switch from left to right just to rotation from night back to day. So if he is doing that at 5:30 in the morning, if there is a custodian and all of the thermostats and go to the day mode and the school and then perhaps the next shift of custodians and leaves at 7:00 or 8:00 in the night and then they switch that same manual switch from the day mode back to the night mode and all thermostats go to the exact point where the night mode hopefully saving energy.

John :

And especially in systems that have summer/winter operations that’s typically manual operations. Because we have to index the entire system from heating, and cooling and quite often it will entail starting a chiller. Those kinds of things that have to be done manually. So hopefully that answered the question.

David:

Okay. Edward has his hand raised. Edward, I will give a try and see if we can hear you.

Edward:

Hey, how are you doing? Eddie from Industrial Cooling.

David:

Good morning, Eddie.

Edward:

Good morning! How are you doing?

David:

Thanks for calling.

Edward:

Oh! Thanks for the webinar. We are surely interested in the replacing the DDC pneumatic stats like you said the first prohibitive to change all of the zones and I hear you guys have some kind of system out there that can actually do wireless and retrofit the actual stats added to the background and just change the air hammers over the DDC.

John :

That’s correct. There is a product now. It’s really a thermostat beside of a box that has a receiver, a radio receiver and a small server and it will adjust to the point of the thermostat at the command from the head on system and that’s relatively recent technology. The benefits of which are that if the electronics fail or batteries fail, that kind of thing, we really revert back to a simple pneumatics the thermostat. It’s just that we have added an element of control to adjust the set point that stat, remotely and then do some other neat tricks. So, that is available now. Yes.

Edward:

Are there any slides to the area I can possibly-?

John :

Which area are you down near, Eddie?

Edward:

We are in New Jersey.

John :

Oh! I would have to check. We can look into that if you wish.

Edward:

We like to look at it because you guys have trouble like that. We are thinking of probably will do a DCC on the air hammer like you said, but we got to keep that. We can’t do the zones.

John :

Right. Actually that’s the best thing to do is to call John Dempsey. He is listed in the next slide. I think he is probably right after this and he can help you through with that.

John :

If we have some other questions we will. We have a question from Astor on a text. What is the typical costs difference between pneumatic and DDC systems?

John :

Are we talking retrofit, replacing like for like? Are we talking about putting a DDC front end on existing pneumatic systems that is somewhat subject to the installation?

David:

Do you want to give Astor a chance to follow up with a call question or do you want to move on or do you want to try to address it now?

Carl:

I will address it now with some clarifications.

David:

Okay. So we will take the next question then and we will be able to come back to this.

Carl:

Sure.

David:

Okay. Gordon Bay. How do I get a copy of the slide show? And actually what we are going to do is, we are going to send out an e-mail to everyone who registered and attended and which is going to link to a video of the slide show. So it will have audio and visual so that you can copy whatever the questions. We have another text question from Hank. Is there any reference material that we can download? Do you have anything else besides the actual slide show that we can give people?

John :

Not to the best of my knowledge. Unfortunately with the web all the manufacturers and the pneumatics have really good detailed service information but they also have calibration information as well. It will point to special tools that you need techniques and means of doing it properly and I would never endeavor do calibration or service on this without at least of some basic manufacturers’ information. There are ports that are most devices are unmarked and those ports are very critical pressure measurement calibrations. So there is lot of stuff on the web. We can get to most of that material through the ICD website. So if there is a lot of demand for this, perhaps we can start a section just for tech support. But at this point we don’t have it. We just invite people to visit the site and drill through and get the manufacturer’s sheets.

Carl:

David, may be you want to, we are trying to advance the slide to the contact information, but perhaps because there’s a lot of questions around that, if we get advanced the slide one, we could show off the industrial contacts of the folks that want or gave the call Industrial Controls reps.