Fuel system shout-off valve closing time

[Laura24]

Hi!
I really hope that somebody can help me.
I need to find closing time for fuel system shut-off valve (Any valve but best of all would be for motor controled ball valve). Could anyone tell me how to do it or tell me where I can try to find some information?
I have a belief that it is possible to calculate but I heed your help.
Kind regards,
Laura

 

[stanier]

Valve shut off times are critical in systems as they can cause waterhammer events that can be destructive. In the extreme you have the disconnect valves on air bourne refuelling tankers. The break away coupling produces massive pressure spikes. (ref Swaffield & Boldy).

A motor controled ball valve can be used on facilities for shipunloading or loading.

You have not described your application in detail so is difficult to help.

 

[hsbcn]

Ball valves shut off at different rates depending on size, medium, configuration (floating vs. trunnion), age and another array of secondary variable. What valve/medium are we talking about?

My focus: Alloy Valves Duplex Valves Super Duplex Valves Monel Valves Inconel Valves [link titanium-valves.com]Titanium Valves[/url]

http://www.6-moly-valves.com

 

[Laura24]

Now I see that I didn`t explained my problem properly.
I am doing a teoretical research of fuel system and I need a fuel shut off valve. I know that on commercial aircrafts they use hidromecanical solenoid controled valves but information about them is not accessible. So I can use any valve but it should be motor or solenoid controled.So I found that ball valves also could be used in fuel systems. If it isn`t so then maybe you can advise other type of valve for my research.
For my research I need to find closing time and quantity passing through the valve during closing time. Or better would say- I need to know the way how I can do it. Does the way differs depending on all parameters hsbcn (Mechanical) mentioned? Or they are parameters who has an influence but the way stays the same for different valves (like equations) After knowing the time I will decide is it OK with my project or not.
I hope now it clear now.
But thank you for your answers anyway.

Laura

 

[PeterIgg]

For what it is worth, Australia has an authority that covers burner management systems, amongst other things, called the Australian Gas Authority (AGA)

http://www.aga.asn.au/.

Their requirements are that pneumatically operated ball valves (to DN 150) shut (fail closed) in less than 1 second (or vent valves fail open in less than 1 second). It is covered by a standard, AS 4629. I also know that Canada has a similar association so I would hazard a guess that there would be similar organisations around the world.

 

[bcd]

Just confirming what PeterIgg has posted. For fuel supply to burner management systems, the typical closing time required is 1 second. A few allow up to 5 seconds for the system, but when you break it down into each action that has to happen for the signal to be sent to the valve to close, it leaves around 1 second for the valve to shut. Most of fuel shut-off valves in burners are fairly small ball valves. 1 and 2 inch sizes. Can get as small as 1/2 inch pipe sizes. For larger burners, they can get up to 8 inch. Hundreds of thousands of ball valves used in these applications all over the world and all of them closing this fast. So don't get derailed by waterhammer and other misdirections.

Most are pneumatically operated to open with spring closure. Solenoid valve control the air in/out. Can't think of any electric operator that can close a ball valve in 1 second. Hydraulic operation can achieve these speeds, but is very expensive and messy.

What is used on burner management systems is probably too large for aircraft. If your pipe size is less than 1/4 inch, you have reached the low size limit to practically make a ball valve.

 

[itascot]

for sizes of 1/4" & below I would suggest direct acting solenoid operated valve, no need for a pneumatic actuator to rotate a ball valve, this is space & energy consuming.
Have a look at ITT

http://www.ittaerospace.com/scripts/products/index.asp?p=valves

Ciao,

 

[dgallup]

You have given no indication of the size of the fuel system, type of fuel, system pressure, etc. All of these will have a direct impact on how fast an appropriately sized valve can respond. Typical solenoid fuel injector closing times are under a millisecond. Times will go up from there. Calculating the amount of fuel delivered during the closing event is not easy, it will be highly dependent on the type of valve chosen.

 

[Laura24]

Diameter of pipes: 2,5 - 3 inches
Fuel: JET-A
Pressure: 50 psi
Fuel flow rate: 1400 l/min

 

[bcd]

For your project, it can be calculated fairly easily using a ball valve with spring return pneumatic actuator. Break the 90 degree rotation into steps. Say 10 steps between full open and closed. At step one, the valve is full open. You know the fluid properties and flow rate, but you also need to know the upstream and downstream pressures. First assumption, do the upstream and down stream pressures remain constant or do they change as the valve closes to a higher maximum differential pressure when shut. Make a graph of DP versus valve position so you can calculate the flow through the valve at each step of closing. Now for the speed of closing. You have to know an appropriate actautor size so you know the spring force and air volume inside. You also have to know the Cv of the solenoid exhausting the air. First step on time is to determine the delay. How long for the solenoid to shift and how long for excess air pressure to vent before the actuator starts to rotate. Add to this the time it takes to each increment of air volume to exhaust from the cylinder knowing the pressure in the actautor at that point. Add up all the times plus the delay and you will be very close to the actual time.

If your goal is to get mathmetical equations, you'll have to derive them. If you simply want the results, most valve companies can give you the flow versus time of closure fairly easily. We have this capability built into software programs.