MPV-20JFM-Y Minimum Pressure Valve (Red Star)

Technical Specifications

💡 Engineer’s tip: “The 4.5–16 bar figure is not a single fixed factory setting — it’s the working range across which the valve opens and holds pressure stably. Before ordering, check what minimum working pressure your unit is set to: if it’s below 4.5 bar, the valve may open later than needed, leaving the airend under-lubricated for the first seconds after start-up” — Vitalie Boluchevschi, Chief Engineer at Acvatron SRL.

Advantages and Features

1. Extended temperature range. The “Y” version’s seals handle up to +130°C versus +120°C on the base model — useful headroom for compressors installed in poorly ventilated plant rooms or exposed to high ambient summer temperatures.
2. Wide working pressure range (4.5–16 bar). The valve performs correctly both on units set to a relatively low minimum pressure and on installations running at 16 bar, removing the need for a separate variant per duty setting.
3. Compact footprint with full DN20 flow capacity. At roughly 65×45×115 mm and 0.3–0.4 kg, it fits separator tanks with limited mounting space.
4. Integrated check-valve function. One component handles two jobs — maintaining minimum pressure and preventing backflow of compressed air and oil into the compressor when it shuts down.
5. Mounting compatibility with the widely used MPV-20 line. Simplifies replacement on units that already used a DN20 valve from this series.

Installation and Maintenance Guidelines

1. Before replacement, release residual pressure from the oil separator tank and let the compressor cool down.
2. Remove the old valve and check the threaded port on the tank for damage or leftover sealing tape.
3. Thread the new MPV-20JFM-Y valve in by hand, then tighten with a wrench to a controlled torque — don’t overtighten, to avoid damaging the tank’s internal thread.
4. Check the flow direction: the valve must be installed strictly according to the oil circulation diagram marked on the housing or in the compressor’s manual.
5. After installation, run a test start-up and watch the pressure gauge — pressure in the separator tank should build up smoothly, with no sudden spikes.
6. Periodically (per the unit’s maintenance schedule) check the joint for tightness and confirm there’s no oil seepage around the valve.

Compatibility and a Warning About Mix-ups

The MPV-20JFM-Y belongs to the DN20 line of RedStar’s MPV series and, by mounting dimensions, is compatible with most small and medium-power screw compressors that use an MPV valve of this size as standard.

⚠️ Important when ordering. Don’t confuse the base MPV-20JFM model with the MPV-20JFM-Y variant — they look identical and share the same mounting dimensions, but the “Y” version is rated for a higher operating medium temperature (+130°C vs +120°C) due to a different seal material. On compressors running in hot rooms or under high thermal load, fitting the base version instead of “Y” can accelerate seal ageing and cause the valve to lose its seal. Also don’t confuse DN20 valves with other diameters in the MPV series (e.g., DN15 or DN25) — the connection thread and flow capacity differ, and a valve of the wrong size simply won’t fit the tank’s port.

Common Replacement Mistakes

• Fitting the base version (without the “Y”) on a compressor operating in a hot room — leads to premature seal wear.
• Overtightening the threaded joint during installation, damaging the thread inside the oil tank housing.
• Ignoring flow direction during installation — the valve loses its check-valve function, allowing oil and air backflow when the compressor stops.
• Starting the unit right after replacement without watching the pressure gauge — misses the chance to catch a valve that isn’t holding minimum pressure.
• Ordering “by eye” from a photo alone, without confirming the DN diameter and thread type of the tank port.

Practical Application Examples

• Light industry: maintaining stable air pressure for automated sewing and textile lines.
• Auto repair shops: powering pneumatic impact wrenches, lifts, and tyre-changing equipment.
• Furniture manufacturing: operating pneumatic staplers and workpiece clamping systems.
• Paint booths: consistent air supply for spray guns without pressure drops.
• Printing houses: pneumatic drives for printing presses and sheet-fed machines.
• High-temperature production floors: food processing, metalworking — where the “Y” version’s thermal margin matters most.

Expert Opinion

“The minimum pressure valve is a small part, but it decides whether the screw pair gets oil in the first seconds after start-up. I always recommend the ‘Y’ seal version where the compressor room is poorly ventilated or sits next to other heat-generating equipment — in practice, that extra 10°C of margin noticeably extends the seal elements’ service life,” notes Vitalie Boluchevschi, Chief Engineer at Acvatron SRL.

FAQ

What’s the difference between the MPV-20JFM-Y and the standard MPV-20JFM? Only the seal material: the “Y” version is rated for an operating medium temperature up to +130°C, while the base model handles up to +120°C. Connection dimensions and operating principle are identical.

Will this valve fit an oil-free screw compressor? No, the MPV series is designed specifically for oil-injected screw compressors and supports the oil lubrication/separation circuit.

Can the valve be repaired, or does it need full replacement? The design allows for maintenance — check with an Acvatron manager on the availability of seal and spring repair kits for this model.

How can I tell that the minimum pressure valve has failed? Typical signs include a slow rise to working pressure after start-up, excessive oil carryover into the pneumatic line, and abnormal noise from the screw airend during the first seconds of operation.