Every application has unique requirements and functionality. Choosing the best pneumatic valve for the best performance requires knowing how to select based on specifications. The specifications are based on many factors from the type of valve design to the flow of the flow of the valve. This webinar covers the basic valve designs and the best applications for their design. You will learn when an air piloted valve is used versus a solenoid piloted valve, the difference between direct acting solenoid valves from indirect acting solenoid valves and when they are best applied in a project and how quality of air, size and speed contribute to the valve selection. What is Cv? How do response times and fill and exhaust help with valve specifications? Lastly, you will learn how to determine valve failure issues. Overall, this webinar provides technical and practical ways to properly specify a valve and how to troubleshoot in the event one should fail. You will learn: Design types features & benefits Types of actuation Sizing/Flow rates (speed) Fail safe

1. Pneumatics:
Choose the Best Valve for Optimum Performance

2.  This webinar will be available afterwards at
designworldonline.com & email
 Q&A at the end of the presentation
 Hashtag for this webinar: #DWwebinar

3. Paul Heney
Nelson Tansey
Design World
Humphrey Products

4. Pneumatics:
Choose the best valve for optimum
performance

5. • Every application has unique requirements and
functionality. Choosing the right pneumatic valve to
produce your applications optimum results involve greater
attention to detail. The following considerations will lead
to selecting the right valve for the application.

6. •
Balanced design – forces of the
supplied air pressure are neutralized
and as a result coil force only must
overcome the force of the return
spring and minor friction. This
results in reduced actuation force,
lower power consumption, greater
flow and isolation of flow paths.

7. •
Unbalanced designs – in the first
design (coil & plunger), the return
spring is of sufficient force to seal the
valve against the supplied air
pressure. In the second design
(electropact or diaphragm/poppet),
air pressure is the primary force to
return the valve to its original position,
which assures that the valve will return
even if the spring fails. This results in
very simple construction, small size,
low leakage, low cost.

8. • Basic design characteristics
• Benefits of each
• Typical applications

9. • Uses a rubber molded poppet
wrapped around the stem that moves
along the bore of the valve, creating a
seal when the poppet is in its seat.
• Advantages:
o compatibility with a variety of media other
than compressed air
o few dynamic (sliding) seals
o less lubrication
o tolerant of contaminate
o high flow capability
o faster response time due to short stroke

10. • Expands on the poppet design by
use of a diaphragm by using the
outer webbing as a guide for the
poppet into its seat without using
a sliding seal.
• Advantages:
o
o
o
o
o
o
greater reliability
no lubrication
compatible with a variety of media
no sliding seals/strong seal control
high durability
low leak rates

11. • Designed using lapped/shear or dynamic
seals. Results can lead to higher leak
rates, and limited use with media other
than clean air.
•
O-Ring spool design
o
•
Advantages: Small size, high functionality, and least expensive.
Disadvantages: o-ring is mechanically squeezed to create seal and a
significant amount of o-ring surface area remains in contact with the
bore. Design is vulnerable to high friction issues without lube or
CDA. Shorter life cycle.
Baked-on seal design
o
Advantages: Larger in size, relatively inexpensive, medium
functionality, minimal friction, and minimized shifting forces.
Disadvantages: Rubber is bonded and then ground which makes it
very stiff and unforgiving. Has continual leakage which increases
over time.

12. •
Lapped-spool design
o
•
Advantages: Small size and high functionality, spool rides on air cushion which produces minimal friction.
Disadvantages: Requires built in continuous leakage, difficult to perform under certain mountings due to
shifting difficulties, must have CDA and is very expensive.
Poppet design
o
Advantages: Has low friction and most reliable, no sticking because stem and seal don’t slide, resistant to poor
air quality, no lubrication required and is relatively inexpensive. Disadvantages: Larger in size, low functionality,
less attractive.

13. • Consider the application and environmental conditions
o Explosive materials (gas, dust, ammunitions)
o Temperature ranges of the applications (ambient condition)
o Continuous duty, intermittent, latching - how often/for what extent of time will it
actuate
**Note: There are also manual/mechanical operators, however we will not be
touching on those during this presentation.

14. • Air-pilot valves use a remote air signal to shift the valve
and internal air or spring to return it when the air signal
is removed
• Can also use a double air-pilot which uses a momentary
air-pilot signal to shift the valve and a second
momentary air-pilot signal to return the valve to its
original position

15. • Indirect-acting valves utilize a small direct-acting solenoid
valve to pneumatically operate a larger air-piloted valve.
• Require minimum air pressure ratings

16. • Advantages:
o
o
o
o
High flow capacity in smaller overall sizes
Lower power consumption
Greater shifting forces
More variety

17. • Direct-acting valves utilize the force generated by the
magnetic field of the solenoid to operate the valve. When
the electrical current is removed, a mechanical spring
returns the valve to its original position.

18. • Advantages:
o
o
o
o
o
No minimum air pressure required
Extremely low leak rates
Simple construction and more robust at lower comparable cost
Typically multipurpose
More applicable to customization such as greater flow, lower power, and faster
response times

19. • How clean is the air in your system? Is there potential for
contaminate to penetrate into your air?
• Moisture
• Dust
• Particulate

20. • Is there a required rate of flow
• What response times are needed by the valve for your
operation
o Minimum/maximum
• What is the distance from main source to area where work
is being done
o Length of lines

21. • Size the correct valve based on flow rate rather than
actuator port size.
• Using Cv is a quick way to approximate air flow. You
cannot get 100% accuracy from this calculation because
air changes shape, direction, velocity, and relative humidity
at the drop of a Farenheit or Pascal.

23. •
•
•
•
T1 times are measured from point 1 (valve energization) to point 2 (10% of supply pressure detected at valve outlet
port).
T2 times are measured from point 2 (detection of outlet pressure) to point 3 (90% of supply pressure).
T3 times are measured from point 4 (valve de-engergization) to point 5 (10% of supply pressure exhausted from outlet
port).
T4 times are measured from point 5 (detection of pressure drop) to point 6 (90% of supply pressure exhausted).
AC/DC Voltages
Coil
Voltage
T1
T2
T3
T4
DC
0.010 sec.
0.001 sec.
0.005 sec.
0.002 sec.
AC
0.010 sec.
0.001 sec.
0.018 sec.
0.002 sec

24. •
•
3 Way, 24 VDC
100 psig air supply
•
Volume = 0.785 x Diameter2 x stroke or length
•
•
•
Cylinder Volume = 3.54 cubic inches
Air Line Volume = .044 cubic inches
Total Circuit Volume = 3.98 or 4 cubic inches
•
•
•
•
•
•
•
T1
Time to energize the valve
Time to fill 4 cubic inches
40% of 0.2 for 10 cubic inches
T3 Time to de-energize valve
Time to exhaust 4 cubic inches
40% of .32 for 10 cubic inches
Total Cycle Time
One Air Line (1/8 inch I.D. x 36 inch long)
Air Cylinder (1.062 inch bore x 4 inch stroke)
=0.010 sec
=0.080 sec
=0.005 sec
=0.128 sec
=0.223 sec

25. • Volume of actuator
• Cycle time
Example
2 in bore x 6 in stroke (area x stroke) = 18.8 cu.in = .011 ft cu
1 sec. stroke time
0.65 cfm

26. • What does failure mean to you in your system?
• Actuation (air, solenoid; direct v. indirect)
o What happens to the valve with loss of electrical signal?
o What happens with loss of air supply?
o What happens with increased air supply?
• Force to return (spring, air spring, detent)
• What direction should the valve fail…Fail open/fail closed,
fail locked (last position)

27. •
•
•
•
•
Type of valve – poppet, spool, diaphragm
Air or solenoid
Direct or indirect
Flow rate, size
Failure conditions

28. Design World
Humphrey Products
Paul Heney
pheney@wtwhmedia.com
Phone: 440.234.4531
Twitter: @DW_Editor
Nelson Tansey
NTansey@Humphrey-Products.com
Phone: 269.381.5500

29.  This webinar will be available at designworldonline.com & email
 Tweet with hashtag #DWwebinar
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