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MultiPort Relief Valve

Multiport Relief Valve

The use of a Multiport Relief Valve dampens the pressure swings within deaerators, steam lines and associated components. The Multiport Relief Valve dash pot vapor action provides smooth relief of excess steam to the atmosphere. By limiting operating pressure variances
within the deaerator, it eliminates the need to restack trays, and provides protection to the trays, boiler feed pumps and other equipment.

These valves are enduring! See Replaced After 69 Years!

Technical information

Why is the Multiport Relief Valve Better Than a Standard Pop Safety Relief Valve?

As the deaerator operating pressure increases, the deaerated water is heated to a higher temperature. When the deaerator operating pressure returns to normal, there will be flashing taking place in the storage tank and the boiler feed pump suction piping. When this pressure reduction is sudden, the flashed steam carries large quantities of water with it to the deaerator section causing tray upsets (this is the only deaerator operating condition that will upset trays).
Further, the flashing that is taking place in the boiler feed pump suction piping causes the pumps to cavitate.
If you are using pop type valves to protect your deaerator from over pressure, you may have satisfied the ASME Code requirements from a safety standpoint, but you have not been able to handle the operational problems involved.

The Multiport Relief Valve is a natural for this type of operation and will go a long way in protecting your trays and boiler feed pumps. The pop safety valves are usually set at the deaerator vessel design pressure, which translates into two  considerations:

  1. No pressure control available until vessel design pressure of the unit is reached, which is usually 30 to 50 PSIG, then the valve blows at the relief valve set pressure.
  2. Allowing the pressure to climb this high will heat the water to a temperature far exceeding the normal boiler feed pump design of 250 ºF. Double trouble!

Key benefits

Design Advantages
• Controlled steam atmosphere
• Easy set pressure adjustment
• Alloy Steel springs for high temperature and Chrome Vanadium Steel springs for medium and low temperatures
• Body is cast iron for applications to 500 ºF and cast steel for 600 ºF applications
• Discs are vapor cushion gradual lift non-pop type with replaceable resilient seating surfaces
• Built for long service life, many COCHRANE® by newterra valves have been in service for fifty years and some for as long as eighty years

Features

Proven Safety
COCHRANE® by newterra Multiport Relief Valve springs cannot be compressed solid nor can the valve be locked closed by external adjustment. When springs are compressed to a maximum point by handwheel adjustment, the valve discs will open upon overpressure. Operating components are internal to the valve, which precludes tampering.

COCHRANE® by newterra Multiport Relief Valves are designed for maximum safety. The valve and springs are designed for the maximum initial relief pressure indicated on the nameplate. This pressure cannot be exceeded by external adjustment even though the valve is fully adjustable to all pressures within the zero to maximum pressure.

A COCHRANE® by newterra Multiport Relief Valve should be installed following every pressure reducing station on all low pressure exhaust steam systems using supplementary reduced live steam. This will provide absolute protection should the reducing valve fail in the open position.

COCHRANE® by newterra Multiport Relief Valves are provided with multiple resilient surfaced vapor cushion discs (on standard brass trim valves) which are non-popping, cushion lift, cushion closed and tight reseating. The seating surface, an extremely resilient high temperature thermoplastic material, allows movement yet helps provide a reliable “soft seal” that prevents leaking. Since this piston seat and disc assembly seats without leaking and reseats faster than other types of  assemblies, useful steam is never wasted. The net result is a reduction of operating costs by saving steam.

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