Cashco 3400 User Manual
Page 5
5
IOM-3400
SECTION VI
VI. TEST PROCEDURE
To Calculate Weight of Pallet Assembly:
Table 2 shows the pallet weight per unit of pressure
or vacuum setting. The total pallet assembly weight
is determined by multiplying the desired set point (in
the appropriate units) by the incremental weight per
unit listed in Table 2.
For Example:
4” Model 3404 CS - if the desired setting is 5 oz/in
2
Table 2 shows that for a 4” vent, the pallet would
weigh 2.05 lb per oz/in
2
So the pallet assembly for a 5 oz/in
2
setting would
weigh: 2.05 lbs/oz/in
2
x 5.0 oz./in
2
- 10.25 lbs
Valve Concepts allows a deviation from this
theoretical weight of ± 3.0%.
To Determine Diaphragm/Seat Leakage:
After both pallets’ weight has been determined and
verifi ed for the required setting, reassemble the vent
and mount on a Tank Vent Test Stand and slowly
raise the pressure at the fl ow rate of 1.0 SCFH.
ACCEPTANCE CRITERIA:
The pressure gauge shall maintain a pressure equal
to or greater than 90% of set pressure for a one
minute period while the specifi ed fl ow rate is main-
tained. Note: Valve Concepts acceptance criteria
exceed the requirements of API. API 2521 states
that if the rate of leakage does not exceed ½ SCFH
for 6 inch size and smaller, or 5 SCFH for 8 inch and
larger, at 75% of set point, then a vent is considered
satisfactory for all practical purposes.
If the vent fails to meet the 90% criteria, it must
be disassembled and the seat, pallet, and or dia-
phragms repaired or replaced.
A test report should be completed for each vent. The
report should indicate the total pallet weight and the
pressure achieved at the Test Flow Rate for both
pressure and vacuum. Other general information
such as serial number, model number, material of
construction, set pressure and vacuum, etc. should
be included in the report.
The test report should be kept with the Valve Main-
tenance Records.
TABLE 2
Nominal Pallet Assembly Weight Per Unit of Pressure lbs (kg)
SET Point
Units
VALVE SIZE
2” VTA
2” PV
3”
4”
6”
8”
10”
12”
Lb (kg)
Lb (kg)
Lb (kg)
Lb (kg)
Lb (kg)
Lb (kg)
Lb (kg)
Lb (kg)
1.0 oz/in
2
0.25 (0.11) 0.55 (0.25) 0.93 (0.42) 2.05 (0.93) 3.50 (1.59) 5.45 (2.47) 7.71 (3.50) 9.17 (4.16)
1.0 in WC
0.15 (0.07) 0.32 (0.14) 0.54 (0.24) 1.18 (0.53) 2.03 (0.92) 3.15 (1.43) 4.46 (2.02) 5.30 (2.40)
1.0 mbar
0.13 (0.06) 0.13 (0.06) 0.22 (0.10) 0.48 (0.22) 0.81 (0.37) 1.26 (0.57) 1.79 (0.81) 2.13 (0.97)
Line Size
10 mil
20 mil
30 mil
40 mil
2” VTA
7.00
34.00
40.00
n/a
2” P/V
4.50
23.50
33.00
40.00
3” P/V
3.50
18.00
25.00
40.00
4” P/V
2.25
12.00
17.00
40.00
6” P/V
1.75
9.25
13.25
40.00
8” P/V
1.75
7.50
10.50
40.00
10” P/V
1.25
6.25
8.75
40.00
12” P/V
1.00
5.75
8.00
40.00
TABLE 3
Maximum Pressure Setting in oz/in
2
Vs. Diaphragm mil