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| Any given application requires proper
sizing of the valve. If the valve selected is too small, flow
conditions will not be met. If too large, system cost will be
excessive. NPT (national pipe thread) ports provide an easy method
of plumbing and installing various types of valves. If you have an
existing valve with NPT threads, identifying the correct pipe size
is easy, just measure the actual thread diameter and then refer to
the NPT Thread
Identification Chart to find the corresponding NPT pipe size (do
not be confused, the actual thread measurement is not the same as
the NPT pipe size). It is also a good idea to measure the threads
per inch. For new applications, verifying the flow rating of the
valve is usually adequate when selecting the pipe size. Click on a
valve stock number to find the flow rating.
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| The orifice size is the diameter of the
flow path passing through the valve. The orifice size directly
affects how much fluid can pass through the valve in a given amount
of time. The larger the orifice size - the larger the flow rate.
Click on a stock number to find the minimum and maximum flow ratings
of each valve. |
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The maximum pressure rating for most
solenoid valves is listed as “Maximum Operating Pressure
Differential”. This is the maximum differential pressure between the
inlet and outlet sides of the valve against which the solenoid can
safely operate the valve. It is safest to regard supply pressure as
the maximum operating pressure differential.
The minimum
pressure rating for most solenoid valves is listed as “Minimum
Operating Pressure Differential”. Some pilot-operated valves require
a maintained minimum differential pressure between the inlet and
outlet sides of the valve for the valve to function properly. This
simply means that a minimum flow through the valve is required in
order to generate the required differential pressure. Click on a
valve stock number to find the minimum flow required (if any) to
generate the minimum pressure requirement. If you are not sure or
unable to supply the minimum flow, consider a valve with a zero
minimum pressure differential, air actuated piston valves or
actuated ball valves. |
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| The maximum pressure rating for most
valves is the maximum pressure (PSIG) allowed for the media flowing
through the valve. This is the maximum pressure at which the valve
can safely operate. The maximum pressure may also be based on
certain media or temperature restrictions.
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| The vacuum range for most valves
suitable for vacuum service is the maximum vacuum (INHG) allowed for
the media flowing through the valve. This is the maximum vacuum
pressure at which the valve will operate. The maximum vacuum range
may also be based on certain media or temperature restrictions.
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| The body of the valve contains the inlet
and outlet ports, which flow passes through when the valve is open.
Valves are available in a wide variety of body materials including
corrosion resistant brass, stainless steel, aluminum, bronze, carbon
steel, and engineered plastics. The wetted parts (parts in contact
with the fluid media) are shown in the specification charts under
“construction”. All materials of construction should be compatible
with any given application and are generally determined by the
operating environment, the process fluid media, durability, and
economics. General service valves with brass bodies and NBR (buna-n)
seals are some of the most popular valves, compatible with most air,
water and light oil applications.
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Seal material selection depends mostly
on the process fluid media, fluid temperature, and operating
pressure differential requirements. Following is a list of the most
common valve sealing materials:
NBR (Buna-N) - the
standard resilient-type seating and sealing used in most valves. It
has excellent compatibility for most air, water and light oil
applications. Useful temperature range 0 to 180 degree F.
EPDM
(Ethylene Propylene) – selected for applications above the NBR
temperature range, such as handling hot water and steam. EPDM has a
wide range of fluid compatibility, but is not suitable for
petroleum-based fluids or contaminated fluids (such as lubricated
air). Useful temperature range -10 to 300 degrees F.
FKM
(Viton) – seal developed primarily for use with hydrocarbons
including jet fuels, gasoline, and a wide range of other chemical
media. Useful temperature range -10 to 350 degrees F.
PTFE
(Teflon) – the most chemical resistant of any seal material.
Useful in a very wide range of temperatures.
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| Solenoid valve coil voltages are
available in either VAC (volts AC) or VDC (volts DC). The most
common coil voltages are listed in the charts. Contact customer
service to check availability of other voltage ranges not listed.
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| Two-way normally closed valves have one
inlet and one outlet pipe connection. The flow is shut-off (blocked)
when de-energized and open (allows flow) when energized.
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| Two-way normally open valves have one
inlet and one outlet pipe connection. The flow is open (allowing
flow) when de-energized and closed (blocking flow) when energized.
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| Two-way normally closed valves have one
inlet and one outlet pipe connection. The flow is shut-off (blocked)
when de-energized and open (allows flow) when energized. The slow
closing valve uses a snubber to slow the disc closing speed to
protect the system against water hammer damage more effectively than
most other techniques. Pressure spikes due to water hammer are
reduced to a point eliminating the need for suppressors or other
controls in most water systems. |
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| Three-way normally closed valves have
three pipe connections. When the valve is de-energized, the pressure
port is closed (blocking flow) and the cylinder port (outlet port)
is connected to the exhaust port. When the valve is energized, the
pressure port is connected to the cylinder port (outlet port) and
the exhaust port is closed. These valves are commonly used to
control single acting spring return cylinders and actuators.
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| Three-way normally open valves have
three pipe connections. When the valve is de-energized, the pressure
port is connected to the cylinder port (outlet port) allowing flow
and the exhaust port is closed (blocked). When the valve is
energized, the pressure port is closed (blocked) and the cylinder
port (outlet port) is connected to the exhaust port.
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| Three-way multi-purpose universal valves
have three pipe connections. Pressure can be applied at any port
allowing the valve to be used as a 3-way normally closed, 3-way
normally open, diverter valve (inlet flow is diverted to either
outlet 1 or outlet 2), or as a selector valve (2 separate inlet
ports with 1 outlet port). |
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| Four way valves are generally used to
operate double-acting cylinders or actuators. They have four or five
pipe connections: one pressure port, two cylinder ports and one or
two exhaust ports. When the valve is de-energized, pressure is
connected to cylinder port A and cylinder port B is connected to the
exhaust port. When the valve is energized, pressure is connected to
cylinder port B and cylinder port A is connected to the exhaust
port. |
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| These solenoid valves operate the same
as a standard 3-way normally closed type valve with the added
benefit of a larger exhaust orifice for quick exhaust. Increased
exhaust capacity significantly reduces cycle time for single acting
spring return actuators. |
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| These solenoid valves mount directly
onto single acting and double acting actuators using the industry
standard Namur mount. Many of these valves can be converted from
3-way operation to 4-way operation by simply selecting the proper
sandwich plate. These direct mount pilot valves eliminate the need
for piping the valve to the actuator, and allow for fast, easy
installation on the actuator. |
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| Cryogenic service solenoid valves are
designed to withstand severe temperatures associated with
controlling cryogenic fluids at temperatures to –320 degrees F.
Typical cryogenic fluids include liquid oxygen (-297 degrees F),
liquid argon (-303 degrees F), and liquid nitrogen (-320 degrees F).
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| Pneumatic actuators are a compact and
cost effective method of automating ball valves. Spring return
models use air pressure to rotate the actuator and open the ball
valve. Upon loss of air or power, springs within the actuator return
the valve to the normally closed position. Typically a 3-way
solenoid valve is used to operate an air actuated spring return
actuator. Many Namur 4-way direct mount valves can be converted to a
3-way function for use with spring return actuators, saving space
and plumbing. |
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| Pneumatic actuators are a compact and
cost effective method of automating ball valves. Double acting
models use air pressure to rotate the actuator, which both opens and
closes the ball valve. Double acting actuators are typically used
when the spring return (spring close) feature is not required and
provide a very reliable and lower cost package. Typically a 4-way
solenoid valve is used to operate the actuator. Namur type solenoid
valves can be direct mounted to the actuator, saving space and
plumbing. |
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| Air actuated spring return piston valves
use air pressure to retract the actuator and open the valve. Upon
loss of air or power, springs within the actuator return the valve
to the normally closed position. Typically a 3-way solenoid valve is
used to operate an air actuated spring return actuator.
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| Electric actuators use a reversing
electric motor and gearbox to rotate the ball valve open and closed.
Typically, electric power continuously supplied to one terminal will
rotate the actuator 90 degrees opening the ball valve. Supplying
power to a second terminal will reverse the rotation and return the
ball valve back to the initial position. Limit switches at each end
of travel will automatically stop the actuator, even when power is
maintained. Most actuators provide an electric signal at each end of
travel for remote monitoring of the valve position.
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