Manufacturer of Temperature and Pressure Instruments and Controls Since 1882

905 Waverly Avenue, Holtsville, NY, 11742


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The Weiss line of Diaphragm Seals, in conjunction with Weiss pressure indicators, offers instrumentation that's rugged and carefully calibrated to withstand the most severe industrial, process or OEM service. Our diaphragm seals are available in a variety of metal housing materials and process connection sizes to fit most requirements.



Series DS/DV/DT


Max. Pressure/Temperature Limits: Vacuum thru 2300 psi to 100°F, 1500psi to 200°F,

600 psi to 400°F.


Top Housing: 1/4" or 1/ 2" NPT (304S.S. standard)


Diaphragm: 316S.S. welded or Viton* or Teflon**


Nuts and Bolts: Stainless Steel


Lower Housing: 1/4" thru 1" NPT



*Viton is furnished for Vacuum, 15 psi, 30 psi and Compound 30-0-15psi ranges.


** Teflon is available for ranges to 200 psi. Ranges 0-30" HG, 30-0-15 psi, 30-0-30 psi. Silicone Filling only.



Ordering Code:  ____-DS______-_____

                              A   -DV B C D -DT


DS= 316ss

DV= Viton

DT= Teflon

Ex: 25-DS12-50

A. Top Connection B. Flushing/No Flushing C. Lower Housing Material
D. Process Connection
25=1/4" NPT 0=No flushing conn. 2=316SS 25=1/4" NPT
50=1/2" NPT 1=Flushing conn. 50=1/2" NPT
75 =3/4" NPT
10 = 1" NPT

LIQUID FILLINGS: Food-Grade Glycerine © Silicone DC200


The Series MD/MN is a compact, lightweight, economical diaphragm seal. The upper and lower housing, as well as the diaphragm, are type 316 stainless steel - all welded together making a one piece integral unit, ideally suited for those applications where space is a factor.


The use of a hermetically sealed, liquid filled pressure gauge in conjunction with either a MD or MN seal protects the indicating gauge from both the process medium and atmospheric conditions, as well as reduces pointer fluctuations due to vibration and pulsation.



Series MD

Opr. Pressure: 60 psi thru 1000 psi

Temperature Limits: -5 to 300°F

Top Connection: 1/4" or 1/ 2" NPT

Process Connection: 1/4",1/2" or 3/4" NPT

Ordering Code: ___-MDN2-____

                             A                 B

                           Ex: 25-MDN2-50


A. Top Connection

25=1/4" NPT

50=1/2" NPT


B. Process Connection

25=1/4" NPT

50=1/2" NPT

75=3/4" NPT


Series MN

Opr. Pressure: 100 psi thru 1000 psi (minimum scale range 0-200 psi)

Temperature Limits: -5 to 300°F

Top Connection: 1/4" NPT

Process Connection: 1/4" or 1/2" NPT

Ordering Code: 25-MNN2- X

                            Ex: 25-MNN2-25


X. Process Connection B.

25=1/4" NPT

50=1/2" NPT



REMOTE MOUNTING: Stainless Steel Plain Seamless or Armored Capillary with Stainless Steel Fittings can be provided for remote mounted applications. Fittings are available in 1/4" or 1/2" NPT.

© 2018 Weiss Instruments LLC, 905 Waverly Avenue, Holtsville, NY 11742 • 631.207.1200

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