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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.
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