Groth 1720A - Manual (Page 8)

8
TEST PROCEDURE:
1. A chart showing nominal pallet assembly
weights for three common units of pressure is
shown below in Table 5. Before starting to
reassemble a valve, calculate the nominal
pressure and vacuum pallet assembly
weights. Weigh both pallet assemblies to
ensure the correct settings.
2. After final assembling, mount the valve on
a Tank Vent Test Stand (TVTS) and slowly
raise the pressure to achieve a flow rate of .5
SCFH.
ACCEPTANCE CRITERIA: The pressure
gauge shall maintain a pressure equal to or
greater than 75% of set pressure for a one-
minute period while the specified flow rate is
maintained.
3. If the valve fails to meet the 75% criteria, it
must be disassembled and the seat, pallet,
and or diaphragms repaired or replaced.
4. Complete a Test Report indicating the
actual pallet assembly weight and the peak
pressure achieved at the specified Test Flow
Rate.
5. A copy of the Test Report shall be
maintained with the Valve Maintenance
Records.
TABLE 5 - Nominal Pallet Assembly Weight Per Unit of Pressure (*)
Valve Size
SET 2" 3" 4"
[Lb.] [kg] [Lb.] [kg] [Lb.] [kg]
1.0 OSI 0.41 0.18 0.84 0.38 1.42 0.64
1.0 IN WC 0.24 0.11 0.48 0.22 0.82 0.37
1.0 mbar 0.09 0.04 0.19 0.09 0.33 0.15
Example: Pallet Assembly Weight Calculation (PAW)
4" Valve set at 7.5 OSI
Read weight at 1.0 OSI from table Weight = 1.42 Lb.
Multiple weight by set pressure PAW (*)= 1.42 x 7.5 = 10.7 Lb.
(*) = Includes pallet, retainer plate, stem, diaphragm, weight plates and fasteners.
The following Table shows the maximum pressure and vacuum settings for the weight loaded
1720A relief valve that can be achieved without the use of special spacer rings between the cover
and body. Consult the factory for higher settings.
TABLE 6- Maximum Vacuum Settings With Lead Weights & No Spacer Ring
Valve Size OSI IN WC mbar
Vacuum 2"-3"-4" 10 17 43
Pressure 2"-3"-4" 33 57 142
WARNING: Table 7 on Page 9 shows the maximum envelope dimensions for the weight blocks to
ensure that a valve will achieve rated flow capacity. DO NOT exceed these dimensions as pallet
lift could be restricted. Pallet lift restriction can cause the tank to be over-pressured to achieve the
valves’ rated flow capacity.