Brochure

Thermoplastic Valves Product Guide & Engineering Specifications
Valve Types
Page 711 Suitable for Oil-Free air handling to 25 psi, not for distribution of compressed air or gas Spears
®
Manufacturing Company
Due to Material Cost Variations, Prices Sub
j
ect to Chan
g
e. Check On-line Catalo
g@
www.spearsmf
g
.com
Since 1969, Spears
®
Manufacturing Company has developed high quality thermoplastic piping system components to
b
etter meet industry needs. Spears
®
thermoplastic valves have been developed through years of product improvemen
t
testing, combined with the latest in computer aided engineering and manufacturing technology. Today, Spears
®
valves
are recognized for their quality, reliability and long service life. Backed by the best in customer service and produc
t
availability, Spears
®
valves are the first choice for use in a wide variety of applications, including Industrial &
Chemical Processing, Turf & Irrigation, Pool & Spa, and numerous Original Equipment Manufacture products.
Valve Function Basics
Ball Valves
Ball valves derive their name from the on/off function accomplished by means of a flow-controlling ball located i
n
the center of the valve body. A hole through the center of the ball (valve bore) connects the inlet and outlet sides o
f
the valve for fluid stream transfer. The ball rotates 90° on an axis perpendicular to the fluid stream in order to bloc
k
flow in the “off” position. The ball is held in place between two valve seats, which serve as a “bubble tight” seal off,
while providing lubrication during valve operation. Elastomer O-rings are used in the stem and seal carrier to preven
t
fluid leakage. Pressure drop is virtually eliminated in the full-open position, since the valve bore is the same size as
Schedule 80 system piping. The T-Style ball valve is a special configuration incorporating a Tee fitting at one end o
f
the valve. This design maintains close proximity of the valve to the fluid mainline to minimize “dead leg” of potential
fluid accumulation, where required by specific application.
3-Way Ball Valves
3-Way ball valves are “diverter” style ball valves that provide an additional port to redirect the fluid stream. Valve
configurations are either vertical (bottom branch port) or horizontal (side branch port). Multiple ball-port options are
available in which different hole patterns in the valve ball provide alternative paths to divert flow. These diverte
r
style 3-Way ball valves have no shutoff on the branch ports.
Check Valves
Check valves are automatic valves that open with forward flow and close with reverse flow. Exact operation will vary
depending on the type of check valve mechanism. These include a ball (Ball Check), a swinging disc (Swing Check),
a
“double disc” (Butterfly Check), a weighted plug (Y-Check), and spring assisted types of check devices. These include
a spring assisted swinging disc (Spring Check) and a spring mounted linear disc (In-Line Spring Check). Regardless
of type, a check valve has a closure device positioned in the valve body between inlet and outlet so that the flui
d
stream is easily transmitted in the direction of flow, but is allowed to move against the check device in the event o
f
flow in the reverse direction. Reversed flow is stopped or held in “check” by fluid backflow pressure which seats the
closure device against the valve body. Standard elastomer O-ring seals are used in all Spears
®
Ball Check Valves an
d
Industrial Swing Check Valves. Utility Swing and Spring Check Valves, and Butterfly Check Valves use an elastome
r
membrane seal; In-Line Spring Check Valves and Y-Check valves use an elastomer seat. Spears
®
Check Valves have
b
een carefully engineered to minimize pressure drop and can be installed in either horizontal or vertical positions,
within the limitations of the specific type of closure device. Ball Check Valves are well suited for general applications
of fluids free from debris and entrained solids. Butterfly Check Valves have minimum space requirements and, along
with Swing Check Valves, are better for use with fluids containing solids or debris. Swing Check Valves additionally
allow higher volume of fluid transmission. Industrial Swing Check models can be fitted with an optional counte
r
b
alance device to further control closing speed. The Utility Spring Check Valve (spring assisted Swing Check) aids i
n
valve closing, while the In-Line Spring Check can be adjusted for resistance to opening pressure.
The in
f
ormation contained in this publication is based on current in
f
ormation and Product design at the time o
f
publication and is subject to
change without notification. Our ongoing commitment to product improvement may result in some variation. No representations, guarantees
or warranties of any kind are made as to its accuracy, suitability for particular applications or results to be obtained therefrom. For verification
of technical data or additional information not contained herein, please contact Spears
®
Technical Services Department [West Coast:
[phone] — East Coast: [phone]].