×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Valve Stroking Speed

Valve Stroking Speed

Valve Stroking Speed

(OP)
Can anyone help how to determine the Solenoid/Air Filetr Regulator Cv required for attaining stroking speed in a Rotary Valve

I have details like this

Actuator Volumetic displacement - 165 litres
Ball Valve closing time reqd - 15 Secs
Ball Valve Opening time reqd - 15 Secs

is there any caluclation available to calculate the Cv required to attain this stroking time?

Advance thanks for the help.

RE: Valve Stroking Speed

Practical advice:

Solenoid valves will for any certain nominal diameter vary greatly (depending on type and brand) in real Cv. Cv or air capacity might be given on different basis.

1. Check actual nominal light opening of the solenoid valve.
Exsample: a 1/4" valve can be anything from less than one mm nominal opening up to 6mm.

2. Check the basis (nomenclature) for the given capacity for the solenoid valve.

3. Any qualified (good)solenoid supplier will give you directly the answer to your question. You have to make some assumptions though.

4. It is always wise to go up in bore on the solenoid to have enough capacity, and then throttle with throttle valves to reduce actuator speed.  Remember that not only solenoid valves but also pipelines, inlet to actuator and internal actuator borings (if any) will influence speed, also sufficient air pressure and air amount available.

5. A nominal bore 1/4" with 6mm throughlet and Kv about 1,2 (Cv = kv times 1,2 = 1,44) might be sufficient, based on an assumption of 167 l/15 seconds times 3600 seconds -> 40Nm3/hour (Qn) necessary. You also have to assume the pressure difference.  For supercritical: Qn=13,36 x P1 x kv for subcritical: Qn = 26,7 x kv x (root of deltaP times p2).

P1 being supply pressure, P2 pressure inside actuator to get sufficient amount in at a pressure to move the avtuator.

As the actual mecanical performance and necessary torque is unknown, I would be much more comfortable selecting a 1/2" with nominal bore 12mm, kv=3,0 (Cv =3,6), and throttle down to suitable speed for the actuator.

 

RE: Valve Stroking Speed

Find your local Automax distributor and ask for a copy of Autosize 3.1.  It has a routine for calculating stroke times with known displacement and Cv of accessories.  Also it works backward and will give you a required Cv if the volume and stroke time are specified.  

Automax is a Flowserve product.  Look in flowserve.com, in the sales locator, and you can contact your local Automax distributor.   

RE: Valve Stroking Speed



No, you would have to define x (the travel) for your rotary actuator.

Geometrically this could perhaps be approximated as the distance along the circle the 'midpoint' of the volume within the actuator travels to complete the turn. Midpoint then defined as the point where half the total volume is further out on the circle and the other half is further in. (Eg. NOT half the distance along the side wall as radius endpoint)

I cannot comment on the quality of the formula in either case, other than that presumptions must be backed by actual experience.

If critical to obtain not more than 15 seconds, I would still have used 1/2 inch and throtteled.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources