Admiral Valve Repair And Supply

ACCUMULATION: Accumulation is the pressure increase over the maximum allowable working pressure of the vessel during discharge through the pressure relief valve, expressed as a percentage of that pressure or actual pressure units.

 

BACK PRESSURE: Back pressure is the pressure on the discharge side of a safety relief valve.  This can either be constant or variable.  

BLOWDOWN: Blowdown is the difference between the set pressure and the reseating pressure of a pressure relief valve expressed as a percentage of the set pressure or actual pressure units.  

BUILT-UP BACK PRESSURE: Built-up back pressure is pressure which develops at the valve outlet as a result of flow, after the safety valve has been opened.  

CHATTER: Chatter is the abnormal, rapid reciprocating motion of the movable parts of a valve in which the disc contacts the seat.  

CLOSING PRESSURE: Closing pressure is the point at which the valve re-closes.  Closing pressure on a test stand may differ from the blowdown, which is the closing pressure under actual service conditions.  

COLD DIFFERENTIAL TEST PRESSURE: Cold differential test pressure is the set pressure at which the valve is adjusted to open on the test stand.  This pressure includes the corrections for back pressure and/or temperature service conditions.  

DIFFERENTIAL BETWEEN OPERATING AND SET PRESSURES: Valves in process service will generally give best results if the operating pressure does not exceed 80% to 90% of the set pressure.  However, on pump and compressor discharge lines, the differential required between the operating and set pressure may be greater because of pressure pulsations coming from a reciprocating piston.  It is recommended that the valve be set as high above the operating pressure as possible.  

FLUTTER: Flutter is the abnormal, rapid reciprocating motion of the movable part of a valve in which the disc does not contact the seat.  

LIFT: Lift is the actual travel of the disc away from the closed position when a valve is relieving.  

MAXIMUM ALLOWABLE WORKING PRESSURE: Maximum allowable working pressure is the maximum gauge pressure permissible in a vessel at a designated temperature.  A vessel may not be operated above this pressure, or its equivalent, at any metal temperature other than that used in its design.  Consequently, for that metal temperature, it is the highest pressure at which the primary safety relief valve is set to open.  

OPERATING PRESSURE: The operating pressure is the gauge pressure to which the vessel is normally subjected in service.  

OVERPRESSURE: Overpressure is a pressure increase over the set pressure of the primary relieving device.  Overpressure is similar to accumulation when the relieving device is set at the maximum allowable working pressure of the vessel.  Normally, overpressure is expressed as a percentage of set pressure.  

RATED CAPACITY: Rated capacity is the percentage of measured flow at an authorized percent overpressure permitted by the applicable code.  Rated capacity is generally expressed in pounds per hour for vapors, standard cubic feet per minute for gasses, and gallons per minute for liquids.  

RELIEF VALVE: A relief valve is an automatic pressure-relieving device, actuated by a static pressure upstream from the valve.  This type of valve is used primarily for liquid service.  

SAFETY RELIEF VALVE: A safety relief valve is an automatic pressure-relieving device which may be used as either a safety ore relief valve depending upon application.  

SAFETY VALVE: A safety valve is an automatic pressure-relieving device actuated by the static pressure upstream of the valve, characterized by rapid opening or pop action.  This type of valve is used for steam, gas or vapor service.  

SEAT TIGHTNESS PRESSURE: Seat tightness pressure is the specified inlet static pressure at which a quantitative seat leakage test is performed in accordance with a standard procedure.  

SET PRESSURE: Set pressure is the gauge pressure at the valve inlet, for which the safety relief valve has been adjusted to open under service conditions.  In liquid service, set pressure is determined by the inlet pressure at which the valve starts to discharge.  In gas or vapor service, the set pressure is determined by the inlet pressure at which the valve pops.  

SIMMER: Simmer is characterized by the audible passage of a gas or vapor across the seating surfaces just prior to “pop”.  The difference between this “start to open pressure” and the set pressure is simmer, and is generally expressed as a percentage of set pressure.  

VALVE TRIM: Valve trim includes the nozzle and disc.