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Ashcroft 300 Elastomer Diaphragm Seal

Elastomer Diaphragm Seal

• Broad selection of materials for meeting various service applications, including Teflon, Viton and Kalrez diaphragms.
• Elastomeric diaphragm is clamped securely between the top and bottom housings by clamp rings, assuring positive seal.
• Top housing is contoured to match diaphragm, minimizing distortion of the diaphragm should the pressure instrument be removed.
• Continuous duty.
• Fill/bleed connection is standard.
• Top housing and diaphragm are non-removable.
• Teflon, Viton and Kalrez diaphragms available in threaded and flanged inlet connections.

Select a link under the "item" tab below to order.

Table 1Table 2Table 3Table 4Table 5Table 6
Table 1Type Number
301Threaded with flushing connection
302Raised Face Flanged ½”,¾” NPT
303Raised Face Flanged 1½”,2”,3”(raised face only)
304In-line Threaded
Table 2Process Connection
Table 3Diaphragm Material
Table 4Bottom Housing Materials
TTeflon flanged steel(⁵)
BHHalar coated stainless steel(⁴)
SUTantalum clad stainless steel(³)
HHastelloy C 276
WInconel “600”
MMonel “400”
DCarpenter 20
JHastelloy C 22
GHastelloy B
S316L stainless steel
C304L stainless steel
Table 5Instrument Connection
Table 6Filling Fluid
CodeFilling Connection to Instrument
CGGlycerin Direct Only
CKSilicone Direct or Flexible Line
CFHalocarbon Direct or Flexible Line
HASyltherm Direct or Flexible Line
Process connection size ¼ NPT, ½ NPT, ¾ NPT, 1 NPT, G ¼, G ½, G ¾, G 1
All connection sizes male or female. Others on request
Construction Bolted top and bottom housing, removable for easy maintenance
Fill port At the side with stainless steel ball and set screw
Flushing connection No
Flushing connection size ¼ NPT female for process connection sizes ¼", ½" and ¾"
1/8 NPT female for process connection size 1"
Maximum pressure Standard in psi/bar 500/35 Viton & Kalrez diaphragm
Metal capsule/diaphragm in psi/bar 2500/172, (also for Teflon diaphragm)
With high pressure ring in psi/bar 5000/350
Instrument connections [female] ANSI/ASME B1.20.1 ¼ NPT, ½ NPT, others on request
ISO 228-1 G ¼, G ½
Material (wetted parts) Bottom housing Steel, stainless steel 316L (1.4404), stainless steel 304L
(1.4306), Monel 400, Hastelloy C, Hastelloy B, Inconel 800,
Nickel, Carpenter 20, Titanium, PVC, Kynar
Diaphragm/capsule (metal type) Stainless steel 316L (1.4404), stainless steel 304L (1.4306), K-Monel, Hastelloy C,
Hastelloy B, Nickel, Carpenter 20, Tantalum
Diaphragm (other types) Kalrez, Teflon, Viton
Material (non wetted parts) Top housing Nickel plated carbon steel, optional stainless steel 316L (1.4404), 316L is standard for ISO connections
Clamps, rings, bolts and nuts Steel, painted black, optional stainless steel 300 (bolts and nuts max. 1500 psi/100 bar)
Accuracy Additional 0,5 % to the specified tolerance of the mounted instrument
Conformity according to RL 94/9/EC
appendix X for mechanical equipment
in potential hazardous areas
Optional, marking File no. 800319037X at notified body 0032, TÜV NORD CERT
The temperature class will by determined by the used measuring device.
Limits for diaphragm/capsule material Kalrez
Temperature 30/350 °F , 0/176 °C
Maximum displacement volume in cm3 8
Filling liquids (temperature range) Glycerin (0/400 °F, -18/204 °C), silicone (-40/600 °F, -40/315 °C), halocarbon (-70/300 °F, -56/149 °C),
Syltherm 800 (-40/750 °F, -40/400 °C), vegetable oil (32/248 °F, 0/120 °C) , Neobee M-20 (0/320 °F, -17/160 °C). Others on request, also depending on selected material and configuration.
Mounting Direct or with capillary
Weight dry in kg 0,8, with high pressure rings 1,1
Accessories, options NACE, pressure gauges, pressure switches, capillaries

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