Mid-West Instrument “Gauge Minder” Pressure Limiting Valve | Model 200

The Mid West Model 200 “Gauge Minder” is a pressure limiting valve designed to be mounted in‑line with pressure instruments to prevent over‑range and instrument damage.

It is intended for use by Australian plumbers, technicians and contractors who need a dependable mechanical device to protect pressure gauges and instruments during testing or service. The primary benefit is reliable protection of instruments from excessive pressure while providing pulsation damping to improve readability and instrument life.

The Model 200 is engineered to automatically shut off excess pressure to the protected instrument, preventing calibration failure and blow‑out. It uses colour‑coded range springs to set a shutoff point between 50 and 5,000 PSI and is supplied with three springs to cover the full range. An adjustable needle valve damps pulsation and reduces pointer oscillation without the need for a separate snubber. The unit is available in aluminium, brass or 316 stainless steel with 1/4″ FNPT connections for 5,000 PSI working pressure and brass or 316 stainless steel with 1/2″ FNPT for 10,000 PSI working pressure. Standard seals are Buna‑N with Teflon backup rings. Alternative seal materials are offered for higher temperature or chemical resistance. The shutoff action is positive and non‑chattering, and the instrument accuracy is unaffected up to the shutoff point, making the Model 200 a practical, cost‑effective safeguard for pressure instruments.

Specifications

• Model Number: 200 (variants: 200‑AO, 200‑BO, 200‑BH, 200‑SO, 200‑SH and special)
• Manufacturer: Mid‑West Instrument
• Working Pressure: 5,000 PSIG (340 bar) for 1/4″ FNPT aluminium, brass and 316 S.S. models and 10,000 PSIG (680 bar) for brass and 316 S.S. 1/2″ FNPT models
• Body Material: Aluminium, Brass and 316 Stainless Steel
• Measurement Range: Shut‑off set point adjustable using supplied range springs to cover 50 to 5,000 PSI (spring colours: Silver 50–120 PSI, Black 100–1,100 PSI, Gold 1,000–5,000 PSI)
• Connections: 1/4″ FNPT x 1/4″ FNPT or 1/2″ FNPT x 1/2″ FNPT depending on model
• Included Components: Three range springs (Silver, Black, Gold), adjustable needle valve, Buna‑N O‑rings and Teflon backup rings (standard)

Common Applications

• Used in the field to protect pressure gauges during commissioning and maintenance of residential and commercial water systems.
• Installed inline with test gauges on industrial hydraulic systems to prevent instrument over‑range during pressure testing.
• Used by trade technicians during pump and compressor testing to protect sensitive instrumentation from pressure spikes.
• Employed in irrigation and municipal testing setups to safeguard gauges when system pressures can exceed instrument limits.
• Applied where pulsation is present and damping is required to stabilise gauge pointers for reliable readings.

The Model 200 is a mechanical pressure limiting valve supplied with colour‑coded range springs and standard Buna‑N/Teflon seals. Optional seal materials are available for different temperature and chemical conditions. The unit is designed for regular use in protection of instruments and for assisting compliance with safe working practice when conducting pressure tests.

This valve is supplied to provide reliable mechanical protection and pulsation damping for pressure instruments, supporting accurate readings and reducing repair and recalibration costs. It comes with a one year warranty for peace of mind and is a practical, trade‑focused choice when instrument protection and operational safety are required.