Piston Type Gauges


  • General specifications: 3000 P.S.I.G. working pressure, aluminum body and end plugs, stainless steel piston; ceramic magnet; Buna N seals; ¼” FNPT end connections.
  • 2½” round dial and “engineered plastic” gauge case with shatter-resistant acrylic lens.
  • Accuracy ±5% full scale accuracy* (ascending).

* ASME B40.100 Grade D (Refer to page 6)

Product Features and Benefits

  • Cost Effective, Simple, rugged, compact design.
  • Glass Reinforced Thermoplastic Gauge Front Is Standard
  • Over-range protection to max pressure.
  • Weatherproof rated to NEMA 4X/IP65.
  • Shatter Resistant Lens
  • Operating Temp. -40° F to +200° F (-40°C to +93°C)
  • Proof Pressure: 12,000 PSI Models:120-A & 120-S
  • Proof Pressure 10,000 PSI Model:122-A
  • Five year Limited Warranty on every gauge.

Mid-West differential pressure gauges are designed to measure pressure drop across Filters, Strainers, Separators, Valves, Pumps, Chillers, etc. as well as for local flow indication and control. Basic gauge functionis to measure the difference in pressure between two points in a system, the differential pressure results are displayed on the gauge dial.

About This Product

DP Range: 0-5 PSID (0-0.35 bar) thru 0-110 PSID (0-7 bar)

Mid-West Piston Type: Model 120 ± 2% or Model 122 ± 5% Full Scale Accuracy. Piston type gauges are primarily designed for liquid applications. Differential Pressure is sensed by the movement of a precisely ground floating piston/magnet in a precision bore against a calibrated spring. Any variation in pressure on either side of the piston/magnet will cause the magnet to move proportionally to the change in differential pressure. A rotary pointer magnet located close to the internal magnet, but outside the pressure housing, follows the movement of the piston magnet and indicates differential pressure on the dial. Piston type DP gauges exhibit a slight amount of bypass as the fluid crosses from the high to the low pressure port. Due to precision sizing of piston and body bore, leakage across the piston will not exceed 15 SCFH air at 100 PSID at ambient conditions.


DP Ranges: PSID, Bar, Kpa, Dual Scale
Body Materials: Aluminum or 316L Stainless Steel
Dial Types: 3-1/2″ & 4-1/2″ Round Uni-Directional Round Anodized Aluminum housing assembly
Seals & Diaphragm Materials: Buna-N, Viton
Carbon or Stainless Steel Pipe Mount Kit
(Pipe Mount option not available for Model 122)
(Pipe Mount option not available with C or D switch option)
Liquid Fill or Maximum Follower Pointer
(Can not combine Liquid Fill with Maximum Follower Pointer options)
Wall Mount Kit (Not available with back connections)
(Wall Mount option not available with C or D switch option)
Connections: 120/122(1/4″FNPT) and 120(1/2″FNPT)



Dial Types: 3-1/2″ & 4-1/2″ Round Uni-Directional Round Anodized Aluminum housing assembly housing assembly, Non-Indication differential pressure switches available.
Seals & Diaphragm Materials: Neoprene, Teflon, Ethylene Propylene and Perfluoroelastomer
Connections: 7/16″-20 Straight thread “O” ring port
Other Options: Reversed high/low process connections, Oxygen Cleaning, Stainless Steel Tags and more…
Electrical Switches: 1 & 2 switch std, Class 1 Div. 1 & Div 2, Explosion Proof


All Model 120/122 differential pressure gauges either conform to and/or are designed to the requirements of the following standards:

ASME B1.20.1

ASME B40.100

CSA-C22.2 No. 14.25 and 30


NEMA Std. No. 250

SAE J514

From: $175.00

  • 122


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