Mid-West Instrument 150 “VARI-DAMP”Adjustable Pulsation Dampener | Model 150

The Mid West Model 150 “VARI‑DAMP” is an adjustable/non adjustable pulsation dampener designed for Australian plumbers, instrumentation technicians and contractors who need reliable protection for pressure instruments and transmitters.

It combines an externally adjustable needle valve for tuning dampening characteristics with a precision ball check to block line surges and fluid hammer, giving practical protection and easier instrument removal without disassembly.

Built for instrument protection in both low‑ and high‑displacement devices, the Mid-West Model 150 uses a fine‑thread needle valve to provide infinitely variable dampening and a stainless steel ball check that seats under surge conditions and meters pressure back to the instrument through a calibrated groove. The design permits on‑instrument installation and a built‑in shutoff for gauge changeout while avoiding the need to disassemble or swap internal components. The unit is offered in brass or 316 stainless steel bodies, in 1/4″ or 1/2″ NPT sizes, and with a range of seal material options to suit different temperature requirements. Simple maintenance is achieved by removing the needle adjusting screw, O‑ring and Teflon backup ring for cleaning.

Specifications

• Model Number: 150 (standard sequence example: 150-BO-00)
• Manufacturer: Mid‑West Instrument
• Working Pressure: 3,000 PSIG (204 bar) for brass 1/4″ unit; up to 10,000 PSIG (680 bar) for 316 S.S. 1/2″ unit depending on configuration
• Body Material: Brass or 316 stainless steel
• Measurement Range: Intended for protection of pressure gauges, differential and compound gauges, and transmitters (not a measuring instrument itself)
• Connections: 1/4″ FNPT x 1/4″ MNPT or 1/2″ FNPT x 1/2″ MNPT
• Included Components: Adjustable needle valve with lock‑nut, precision ball check, O‑ring and Teflon backup ring (installed)

Common Applications

• Installed directly on pressure gauges and transmitters to protect instruments from pulsation, surge and fluid hammer in industrial and plant instrumentation.
• Used on both low‑displacement devices (Bourdon tube gauges, electronic transmitters) and higher‑displacement devices (diaphragm or piston actuated instruments) to stabilise readings.
• Fitted on each input line for double‑ported instruments to prevent cross‑line surges affecting measurement.
• Suited to commercial and light‑industrial pressure monitoring where adjustable dampening without disassembly is required.
• Used during maintenance work to provide a built‑in shutoff for safe gauge removal without requiring a separate block valve (observe torque caution).

Model 150 is a purpose‑built mechanical dampener manufactured by Mid‑West Instrument in the USA. It is intended for protection of pressure measuring devices and not as a primary pressure measuring instrument. Calibration certificates are not provided for the dampener itself; calibration applies to pressure instruments that the Model 150 protects.

This product provides a practical, serviceable way to protect pressure instruments from pulsation and surge while allowing adjustable dampening and straightforward maintenance. It is a trade‑focused component selected for its mechanical reliability and ease of installation.