Valve design and function – Groth 1200A User Manual
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VALVE DESIGN AND FUNCTION:
Fig. 1 - Typical Tank Installation
Tank protection equipment typically includes an
operating valve which is designed to provide
pressure/vacuum relief under normal pump in/out and
thermal breathing conditions. An emergency relief
valve can also provide both pressure and vacuum relief
and normally it is sized to provide pressure relief if there
is a fire in the immediate vicinity of the tank. It may also
be sized by the tank designer to provide protection in
the event of equipment failure (such as the rupture of a
process steam line or an inert gas blanketing system
failing “wide open”) or operator error.
A typical tank installation is shown in Fig. 1 which
includes the following Groth products:
Model 1220A ‘P/V’ Weight Loaded Valve
Model 3000 Gas Blanketing Regulator
Model 2000 Emergency ‘P’ Relief Valve
Pressure Relief: As the pressure in the storage tank
increases, the vacuum pallet is held shut. When the set
pressure is reached, the pressure pallet lifts and
relieves to atmosphere (or to a header if it is a pipe
away valve). See Fig. 2.
Vacuum Relief: As a vacuum is drawn in the storage
tank (for example, when fluid is being pumped out), the
pressure pallet is held shut by atmospheric pressure.
When the vacuum setting is reached, the pallet lifts and
air is drawn in from the atmosphere. See Fig. 3.
Installation Notes: (See Fig. 1 above)
1. Minimum clearance between tank roof and vacuum
inlet port must be at least equal to the valves’
nominal flange bore.
2. Tank nozzle bore must be > or = valve inlet flange
bore.
3.
Inlet and outlet piping loads must be supported by
appropriate structural supports, NOT by the valve
body.
Fig. 2- Pressure Relief
Fig. 3 - Vacuum Relief