INSTALLATION, OPERATION AND MAINTENANCE MANUAL (IOM)
IOM-5400
01-17
SECTION I
I. DESCRIPTION AND SCOPE
Model 5400 Pilot Operated
Pressure Relief Vent
The maintenance of this Pilot Operated Vent Valve
(POVV) should only be done by qualified valve
technicians. It is important that the technician be
familiar with the API and corporate standards,
corporate safety policies and the relief vent
manufacturer requirements. When repair services
are performed by an outside company, the company
needs to be a Cashco factory authorized repair
center which specializes in low pressure venting
devices.
Thus the vent valve is capable of operating at
pressures closer to the maximum allowable
working pressure of the tank. Operating at higher
pressures reduces evaporation and total venting
volume, thereby reducing product loss and the cost
of handling emissions.
Each application must be reviewed to ensure ma-
terial compatibility with all metal and soft good
components with the service conditions. The pallet
assembly, wetted components and tubing are 316
SST. Diaphragm material is FKM, unless specified
otherwise.
The pilot valve is factory set to comply with the
specifications on the purchase order. The adjust-
able pressure range is a function of the installed
spring and will be stamped on the metal nameplate.
The set point pressure may be changed within the
design parameters of the spring while installed on
line or in a maintenance shop. See Section IX for
setting and testing procedures.
This manual is intended to provide recommended
procedures and practices for installation, operation
and maintenance of the Model 5400 POVV. Al-
though this manual cannot cover all possible con-
tingencies, these guidelines will provide safe and
reliable pilot valve performance.
II. VALVE DESIGN AND FUNCTION
The Model 5400 Pilot Operated Vents are used on
liquid storage tanks and other process vessels or
systems to prevent structural damage due to excess
internal pressure. This excess pressure is vented to
the atmosphere.
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, a vacuum may be created when fluid
is pumped out or as atmospheric temperature
decreases. To prevent structural damage, vapor
must be allowed to escape or enter the tank at a
specified flow rate. The volume rate of venting is
dependent on the tank size, displacement rate and
the flash point of the fluid. See API Standard 2000
for procedures to determine venting requirements.
A pilot operated relief vent has two principal
advantages over other relief vent designs:
1. Bubble tight shutoff up to 100% of set point.
2. Full open capacity for pressure relief is achieved
within 10% above set point.
SECTION II
For information on repair centers in your area,
please contact:
Valve Concepts, Inc.
%Cashco, Inc.
607 West 15
th
Street
Ellsworth, KS 67439-0006
(785) 472-4461 (Phone)
(785) 472-3539 (Fax)
ISO Registered Company
