How to Specify a Pinch Valve 
The minimum information our engineers need help
you properly select a pinch valve is described below.
After you define this information, you may convey it to
us in a number of ways: by calling an Acro Applications Engineer at
1-800-672-2276; by e-mailing us at engrs@acroassociates.com;
or by completing our Applications
Review Worksheet and submitting it electronically or via fax
to 925-680-8113.
Required Information for All Valves
What is the application?
From this information, we gain an understanding of your
system operation and performance requirements and allows
us to draw on past experience to better meet your needs.
What is the O.D. and I.D. or wall thickness of the tubing?
This information helps us determine the most appropriate
valve model and pinch
gap.
What is the tubing material, durometer,
and maximum media
pressure?
These specifications establish the required pinching
force.
What is the desired flow rate?
From this information, we can establish a total
opening specification that permits adequate flow. (Often times,
a qualitative answer to this question is sufficient.)
Is position
feedback required?
This information allows us to establish whether a position
sensor should be considered. The specific application details you
provided above will enable us to determine a suitable sensing mechanism.
What valve orientation is required?
Horizontal, vertical or other
What type of valve mounting?
Do you have a specific valve mounting requirement?
What type of sensor output?
Please answer the following additional questions:
For Pneumatic Valves
Will you supply your own 3-way control valve?
What is the available minimum and maximum supply
pressure? This is related to the pinching
force and ensures that the valve will open and close
properly and meet your cycle rate.
For Solenoid Valves
Will you supply your own solenoid controller
(pulse and hold driver)?
Pulse and Hold driver circuits add flexibility
to the system by enhancing operational parameters, such
as the amount of pinch forces, and minimizing heat.
If none is available, the valve must be designed accordingly.
What are the power supply voltage and current
ratings?
This will enable us to design a valve that meets all of
your specifications: coil selection, total
opening, pinching
force, and heat generation.
What is the cycle rate and duty cycle?
These specifications help us design a valve that takes
into consideration heat generation and the corresponding heat
rise, which must be maintained at safe levels. Duty
cycle is expressed as a percentage (%) and is determined
by (ON time) / (ON time + OFF time). For example if a pinch valve
is energized for 1 second out of 4 seconds, the duty cycle is
1/(1+3) = 1/4 = 25%. Factors such as tubing size, hardness, temperature
and media pressure can also affect cycle rate.
What is the maximum on-time?
Very close attention must be paid to the maximum on-time
data provided in conjunction with the duty cycle calculation
to avoid overheating and eventually damaging the valve. The maximum
on-time should take into account the time required to perform
such operations as tubing changes or maintenance in addition
to the actual application requirements.
Is noise a concern?
From this information, we can determine whether sound
dampening devices should be considered.
