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Vaisala HMT338 Humidity and Temperature Transmitter

Humidity and Temperature Transmitter
HMT338

The Vaisala HUMICAP® Humidity and Temperature Transmitter HMT338 is designed for pressurized processes.

Insert or remove probe while the process is running
With “hot tapping”, the probe is inserted directly into the process while it is running, without the need for venting or lowering the process pressure.

The probe is screwed into a ball valve assembly that has been fixed to the process pipe or wall. The adjustable hex nut is hand-tightened to temporarily hold the probe to the process. Then the probe is pushed down to the appropriate depth. The hex nut is tightened with a wrench to lock the probe in its place. Hot tapping is possible in pressures up to 10 bar.

Graphical display of history and measurement trends
From the display, the user can easily monitor operational data, measurement trends and one-year measurement history.

The optional data logger with real-time clock makes it possible to generate more than four years of measured history, and zoom in on any desired time or time frame. The battery backup of the real-time clock guarantees a reliable logging of measured data.

Vaisala HUMICAP®
The HMT338 incorporates Vaisala’s more than 30 years of experience in industrial humidity measurement. The sensor provides accurate and reliable measurement and is immune to particulate contamination and most chemicals.

• Installed through ball valve – can be inserted and removed while the process is running
• Adjustable probe depth
• Pressure tolerance 40 bar
• For temperatures -70 ... +180 °C (-94 ... +356 °F)
• Two probe lengths available

Relative humidity
Measurement range 0 ... 100 % RH
Accuracy (including non-linearity, hysteresis, and repeatability) with Vaisala HUMICAP® 180 or 180R for typical applications
with Vaisala HUMICAP® 180C or 180RC for applications with chemical purge/warmed probe
at +15 ... +25 °C (59 ... +77 °F) ±1 %RH (0 ... 90 %)
±1.7 %RH (90 ... 100 %RH)
at -20 ... +40 °C (-4 ... +104 °F) ±(1.0 + 0.008 x reading) %RH
at -40 ... +180 °C (-40 ... +356 °F) ±(1.5 + 0.015 x reading) %RH
Factory calibration uncertainty (+20 °C) ± 0.6 % RH (0 ... 40 %RH)
± 1.0 % RH (40 ... 97 %RH)
Response time (90 %) at +20 °C (+68 °F) 8 s / 17 s* with grid filter
in still air 20 s / 50 s* with grid + steel netting filter
40 s / 60 s* with sintered filter
Temperature
Accuracy at +20 °C (+68 °F) ± 0.2 °C (± 0.36 °F)
Inputs and outputs
Operating voltage 10 ... 35 VDC, 24 VAC
with optional power supply module 100 ... 240 VAC, 50/60 HZ
Power consumption at +20 °C (Uin 24 VDC) RS-232 max. 25 mA
Uout 2 x 0 ... 1 V/0 ... 5 V/0 ... 10 max. 25 mA
Iout 2 x 0 ... 20 mA max. 60 mA
display and backlight + 20 mA
during chemical purge max. 110 mA
during probe heating (HMT337) + 120 mA
Analog outputs (2 standard, 3rd optional) current output 0 ... 20 mA, 4 ... 20 mA
voltage output 0... 1 V, 0... 5 V, 0... 10 V
Accuracy of analog outputs at +20 °C ±0.05% full scale
Temperature dependence of the
analog outputs
±0.005%/°C full scale
External loads current outputs RL < 500 ohm
0 ... 1 V output RL > 2 kohm
0 ... 5 V and 0 ... 10 V outputs RL > 10 kohm
Max. wire size 0.5 mm2 (AWG 20) stranded wires recommended
Digital outputs RS-232, RS-485 (optional)
Service connection RS-232, USB
Relay outputs (optional) 0.5 A, 250 VAC
Ethernet interface (optional) Supported standards 10/100Base-T
Connector RJ45
Protocols Telnet
Software support Vaisala MI70 link
Ethernet interface (optional) Supported standards 802.11b
Connector Type RP-SMA
Protocols Telnet
Security WEP 64/128,WPA
Software support Vaisala MI70 link
Authentication / Encryption (WLAN) Open / no encryption
Open / WEP
WPA Pre shared key / TKIP
WPA Pre shared key / CCMP (a.k.a. WPA2)
Optional data logger with real-time clock Logged parameters max. three with trend/min/max values
Logging interval 10 sec (fixed)
Max. logging period 4 years 5 months
Logged points 13.7 million points per parameter
Battery lifetime min. 5 years
Display LCD with backlight, graphic trend display of any parameter
Menu languages English, Chinese, Japanese, Spanish, German, French, Swedish, Russian, Finnish


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