Groth 1401E - Manual (Page 2)

1
TABLE OF CONTENTS
GENERAL INFORMATION
Pilot Valve Design and Function 2-3
SAFETY
General Instructions 3-4
INSTALLATION
Inspection and Installation 4
OPERATION AND MAINTENANCE
Modes of Operations
Equipment Options Operation
Troubleshooting Guide
Recommended Spare Parts
Maintenance
Disassembly
Assembly
Recommended Testing & Setting Procedure
Bill of Material
Model Identification
Product Limited Warranty 4-6
6-7
8
8
8
9
9-10
11
12
15
15
LIST OF FIGURES
1. Tank Installation - Safety Equipment
2. Pilot Valve Function-Shut off Condition
3. Operation - Closed Position
4. Operation - Open, Snap Action
5. Operation - Open Modulating
6. Operation - Reseat, Snap Action
7. Operation - Reseat Modulation
8. Options - Vent Piped to Discharge
Header
9. Options - Field Test Connection
10. Options - Manual/Remote Blowdown
11. Body Sub - Assembly
12. Stem Sub - Assembly
13. Test Apparatus
14. Exploded Assembly
15. Cross Sectional Assembly 2
2
5
5
5
6
6
6
7
7
9
10
11
13
14
LIST OF TABLES
1. Pilot Valve Specifications
2. Spring Table
3. Recommended Spare Parts
4. Recommended Bolt Torque
5. Setting Specifications - Pilot Valve 3
5
8
9
11
INTRODUCTION
Pressure and/or vacuum relief valves are used on
liquid storage tanks and other process vessels or
systems to prevent structural damage due to excess
internal pressure or vacuum.
Storage tanks are pressurized when liquid is pumped
in, compressing the existing vapor or when
increasing temperature causes increased evaporation
or expansion of existing vapor. Conversely, vacuum
may be created when pumping out or decreasing
temperature. To prevent damage, vapor must be
allowed to escape or enter the tank at a specified
pressure or vacuum. The volume rate of venting
depends upon the tank size, volatility of the contents,
the pumping rate and the temperature. See API
Standard 2000 for the procedure for determining
venting requirements.
The pilot operated relief valve has two principal
advantages over other types of relief valves:
1). It is bubble tight at 10% below set pressure.
2). It is fully open at 10% above set pressure.
These characteristics permit operating pressures
nearer to the maximum allowable working pressure
of the tank. High operating pressures reduce
evaporation and total venting volume, thereby
reducing product loss and cost of processing
emissions. A tank may also have provisions for
emergency pressure relief due to fire exposure and/or
inert gas blanketing of the vapor space. A typical
tank installation is shown in Figure 1 which includes
a pilot operated pressure/vacuum relief valve, a gas
blanketing regulator and an emergency pressure
relief valve. The emergency valve may also be pilot
operated. Groth Corporation manufactures all of
these devices.
The pilot valve must be carefully maintained by a
knowledgeable valve technician. It should only be
assembled under clean conditions, preferably in a
service shop environment. Carefully read and
understand this manual before attempting to adjust
set pressure or blowdown, or repair the pilot valve.
Groth Corporation offers repair services for all
products manufactured by The Tank Protection
Division.