Groth 1720A User Manual
Page 4

4
SAFETY WARNINGS:
This section is an overview of safety 
guidelines that should be followed during the 
installation, operation and maintenance of 
Groth Pressure/ Vacuum Relief Valves. To 
understand the context of these instructions 
and warnings, it is necessary to completely 
read and understand the contents of this 
manual. 
The purpose of a weight loaded 
pressure/vacuum relief valve is to prevent 
excessive pressure or vacuum in a tank or 
process system. The valve must be designed 
for the proper MAWP and flow requirements 
of the system. Consult API Standard 2000 for 
tank protection sizing procedures. An 
improperly specified or functioning relief valve 
may result in structural damage to the tank or 
system, and can cause severe personal injury 
or death. 
Valves are set at the factory according to 
purchase specifications. Do NOT change 
pressure ratings by adding additional weights 
to the pallet assembly without consulting the 
factory or your local Groth representative. 
Adding weights to a valve may restrict pallet 
lift and reduce the valves’ rated flow capacity. 
DO NOT mix pressure/vacuum pallet 
assemblies. Failure to ensure that both pallet 
assemblies are installed in the correct 
location can change the pressure and 
vacuum relief settings. This can cause a tank 
failure. 
DO NOT attempt to remove the valve from 
the tank or process vessel without first 
bleeding all pressure from the system. 
ALTERNATIVE MEANS OF PRESSURE 
RELIEF MUST BE PROVIDED WHEN THE 
VALVE IS OUT OF SERVICE. 
If the valve has been exposed to process 
vapors while in service. Observe all plant 
procedures and Material Safety Data Sheets 
(MSDS) for the products in the system when 
inspecting, adjusting or servicing the valve. 
Take appropriate safety precautions 
regarding eye protection, respiration and skin 
contact. 
The tank pressure required to discharge the 
normal or emergency venting requirements of 
the tank will be increased by the amount of 
back pressure in the discharge header, on a 
pipe away valve configuration. Maximum 
possible discharge header pressure must be 
considered when sizing the pressure relief 
valve. 
INSPECTION AND STORAGE:
The pressure/vacuum relief valve is carefully 
packaged to prevent damage or 
contamination during shipping. Inspect all 
equipment when it is received; report any 
damage to the carrier immediately. The valve 
should be protected during handling and 
storage. Keep all the ports plugged to 
prevent intrusion of foreign materials. Before 
installation, inspect the unit for indications of 
physical damage or internal contamination. If 
these are observed, the valve must be 
disassembled, cleaned and repaired before 
installation. 
INSTALLATION:
A typical valve installation on a tank or vessel 
is illustrated in Fig.1 on Page 3 using a Model 
1720A Pressure/Vacuum Relief Valve. 
Groth's weight loaded Pressure/Vacuum 
Relief Valves are designed to provide tank 
protection for both pressure and/or vacuum to 
+/-1 PSIG settings. The valves provide full 
rated flow capacity at 100% over-pressure. 
Consult factory for performance under other 
conditions. 
WARNING: The valve must be installed in a 
vertical position as shown in Fig 1. To 
achieve nominal flow capacity, the tank 
nozzle bore must be at least the same 
nominal dimension as the relief valve inlet 
body. 
This series of valves all have 150# ANSI 
flange drilling compatibility. Torque 
guidelines are listed in Table 1. The valves 
are NOT rated for full flange pressure and do 
not require high bolting torque. Consult 
factory for special applications. 
