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I. Product Description:
Weir SPM's Emergency Unloading Valve provides over-
pressure protection for reciprocating pumps, treating lines,
pressure vessels, and other equipment operating under high
pressure, high flow conditions. Compact and simple to
operate, the valve is direct acting, relying on the system's
hydraulic pressure to overcome a preset nitrogen gas force
to relieve. It is externally adjustable from 1000 psi pressure
to maximum setting.
The valve behaves similar to a “highlift” device in that once
it begins to lift, the back pressure is greatly reduced.
Consequently, the valve remains open until the liquid end
pressure decays to approximately 16% (theoretically) of
the initial set pressure. Once the fluid pressure falls below
this approximate threshold, the valve will reseat to its
original set pressure.
Manufactured to Weir SPM's stringent Quality Assurance
System, all pressure bearing components are made from
high quality material. The forged body features an integral
wing union male inlet, suitable for the pressure rating of the
component.
The low-pressure outlet is available with an integral wing
union female connection. Conforming to conditions of
design and performance in API RP520, the SPM Emergency
Unloading Valve is intended for liquid service. It is not
intended for elevated temperatures nor as a safety device in
case of fire.
Available in 3”, this valve offers pressure ranges from 1000 –
15000 psi. The valve is best suited for over pressure
protection in a “slick water” medium. However, it should
work well in drilling mud applications also.
II. Pressure/Temperature Ratings:
IV. Installation:
III. End Connections:
The Weir SPM 3” Emergency Unloading Valve is available in
the following configurations at this time.
Fluid Side Ratings:
3" - 1502M
3" - 1502F 1000 - 15000 15000 Standard -30°C - 110C
INLET
(LOW PRESS)
DISCHARGE
PRESSURE
RANGE
(PSI)
INT. END
NSCWP
(PSI) SERVICE
SEALS
TEMP.
RANGE
Gas Side Specifications:
Low Pressure Working Range: 0 to 800 psi
Recommended Nitrogen Bottle: 2,000 psi
Recommended Rupture Disc: 2,250 psi
Bottle or source gas pressure should be twice maximum
low pressure working range.
Operating Temperature: -22°F to 120°F
(-30°C to 49°C)
Weir SPM’s 3” Emergency Unloading Valve is available with
Weir SPM Wing Union Connections. The nameplate will
indicate the cold working pressure allowable for each
assembly.
Wing union connections on the relief valve are
interchangeable with other union connections of the same
size and figure (pressure rating). Caution must be taken to
avoid mixing different ratings of wing connections. There
are various sizes and figures that are capable of making
marginal connections. Failure to observe good judgement
may lead to failure of components and danger to life and
limb. Always verify working pressure ratings of each
connection before use.
This device is intended to discharge to atmospheric
pressure when it relieves. It should not be subjected to any
significant backpressure. The choice of discharge
connections is offered as a convenience for the user and
does not imply high-pressure capability.
Observe all instructions, cautions and warnings as
noted in this brochure. Failure to do so can lead to
equipment damage, personal injury or loss of life.
The SPM Unloading Valve should be installed in a branch
on the high-pressure pump line (Fig. 1). The valve should
be mounted directly at pump discharge or behind the
discharge pulsation damper, if so equipped.
FIG. 1
Preferably, the valve should be mounted in the vertical
position as shown, to reduce the tendency for
contaminants and particulates in the fluid to collect at the
throat of the main seal. However, any position within
approximately 30 degree declination is acceptable.
The gas regulator and back pressure regulator should be
installed as close to the unloading valve as practical for
good practice. The nitrogen filled high-pressure cylinder
must be secured to avoid danger of movement.
