SpudFiles

What can be done to slow the opening/closing time of a sprinkler valve?

I am using the valves to control house water pressure and I would like the valve to open and close slower in order to prevent/reduce water hammer.

See http://www.water-on-demand.us for full details that describe this invention.

I would think reducing the efficiency of the piloting would help, have you tried reducing voltage to the solenoid?

Adding a stronger spring above the diaphragm could help, although depending on how strong the spring is it could prevent the valve from opening at all. You could also make the equalization hole in the diaphragm slightly larger.

Perhaps stiffening the spring between the diaphragm and housing?? Seems like that would slow down the opening...

If youre willing to modify the hell out of it... you could always drill the cap (like we do all the time for spudgun use) and replace the spring with a larger adjustable spring. ( think adjustable ball detent minus the ball and on a bit larger scale)

Just ideas, never tried to SLOW one down lol. Didnt you know sprinkler valves were for spudding??? such a waste of a valve...

SECOND IDEA- limit the travel of the diaphragm. If it doesn't open as much the flow will be reduced. Take it apart, and where the spring contacts the housing (where we normally drill the hole) add a spacer that keeps the valve from fully opening. To keep the spring tension the same as it was from the factory... cut off "X"mm of spring.... where "X" it the thickness of the spacer you added.

THIRD IDEA- DONT modify the valve at all... just add a flow reducer AFTER the valve. This allows the valve to operate normally and reduces hammer on.

jackssmirkingrevenge wrote:I would think reducing the efficiency of the piloting would help, have you tried reducing voltage to the solenoid?

It is a 24 VAC solenoid.

I tried using 17 VAC with no effect.

I don't know how low it can get.

Stiffening the spring came to mind, however this would probably limit the flow in general and would be akin to restricting the flow. I think what he wants is to slow opening time but keep maximum flow.

Another option could be finding a way to restrict the port which the solenoid seals against.

@JRS- that solenoid port hole is SUPER tiny to begin with and would probably require more work than its worth.

Dunno bout the spring stiffening. Seams to me that even with stiffening (assuming you used the original spring) it would still collapse back to the same minimum thickness, allowing the valve to be in the same open position as it was to begin with (aka fully open).

Im still thinking some kind of gate or butterfly valve AFTER the SV would be a good bet. On the flip side... hammer on isnt really damaging to a system so long as your pipes can handle the pressure change. It usually just causes an annoying noise from pipes vibrating against the wood structure of your house. There are many ways to quell that vibration available in most plumbing shops... like hose clamps that have rubber gaskets. Might be of use to look into installing a few of these in strategic places through the house.

Something along the lines of this

edit for correct link
http://www.mcmaster.com/#pipe-routing-clamps/=9ud7ti
Second edit... keeps changing my link... talking bout the "Rubber-cushioned loop clamps" in the bottom left corner of listed link.

boyntonstu wrote:What can be done to slow the opening/closing time of a sprinkler valve?

I am using the valves to control house water pressure and I would like the valve to open and close slower in order to prevent/reduce water hammer.

See http://www.water-on-demand.us for full details that describe this invention.

Leave the sprinkler valve alone.

Just put an anti-water-hammer valve or two, after the sprinkler valve.

http://www.lowes.com/ProductDisplay?par ... &cId=PDIO1

.

What I would recommend is the proper valve for the job. These valves are motorized and normally off. Applying power opens them with a gear drive. When powered down, they close with a stored charge in a capacitor.

They cost more than a sprinkler valve but they are designed to prevent hammer in zone controlled heating and cooling systems and operate on the pressures you need with very high (better than a sprinkler valve) CV.
http://www.accentshopping.com/product.asp?P_ID=149721
They come in 1/2 3/4 and 1 inch sizes.

Oh and the important spec for your consideration;

Full Open to Full Close (90° turn), 4 seconds

Technician1002 wrote:What I would recommend is the proper valve for the job. These valves are motorized and normally off. Applying power opens them with a gear drive. When powered down, they close with a stored charge in a capacitor.

They cost more than a sprinkler valve but they are designed to prevent hammer in zone controlled heating and cooling systems and operate on the pressures you need with very high (better than a sprinkler valve) CV.
http://www.accentshopping.com/product.asp?P_ID=149721
They come in 1/2 3/4 and 1 inch sizes.

Oh and the important spec for your consideration;

Full Open to Full Close (90° turn), 4 seconds

Good find, thanks.

A copper chamber with a Schrader valve on a T branch, may be the a good way to build a cheap water anti-hammer shock absorber.

At $85 for the BV compared to a $20 sprinkler/anti-hammer it is not clear what is the best choice.

Replacement, repair, material, underground installation, etc....

It make me think.

Thanks again for your input.

Anti-water hammer air shocks have some limitations.

Air dissolves in water so unless the unit has a membrane they go flat. With a membrane, it needs periodic replacement as they fail over time.

They are designed to handle the spike near a faucet. They are NOT designed to prevent cavitation due to rapid shut off of flow into a long pipe. It may fail when subjected the vacuum of cavitation.

boyntonstu wrote:What can be done to slow the opening/closing time of a sprinkler valve?

I am using the valves to control house water pressure and I would like the valve to open and close slower in order to prevent/reduce water hammer.

See http://www.water-on-demand.us for full details that describe this invention.

To properly control the inlet pressure to your inside plumbing, one of these should be installed:

<img src="http://www.hardwarestore.com/media/prod ... ont200.jpg">

To prevent water hammer, you should put one of <a href="http://www.shopwiki.com/_Amtrol+Therm-x ... ">these</a> on the water heater.

I alway hate it when people provide a cure for an ailment when the ailment might not be present.

Add a pressure regulator only if you have excessive water pressure. This means measure your water pressure first.

Florida is relatively flat, so the chances of excess pressure due to being at the bottom of a hill is very slim. The highest elevation in Florida is less than 400 feet. Look it up.

In my state, we have hydroelectric dams taller than the highest elevation in Florida. We are more likely to need a regulator due to being downhill from a water source.

Adding a 60 PSI regulator to a system getting only 40 PSI is a simple waste of money. Adding one to a system with 60 PSI is the same waste. Adding one to a system with 120 PSI of pressure is a very good idea.

A regulator always lowers pressure either by regulation or insertion loss. This will always make a low pressure problem worse.

Personally I live on the top of a hill. I'd be more inclined to add a booster pump than a regulator. My pressure is close to 35 PSI.

As for the addition to the expansion tank, they can be added anywhere. Near a water heater is popular as it is in an area not subject to freezing and it has the room. It can be added anywhere there is space and there is no check valve between the heater and expansion tank.

Due to the cavitation issue mentioned earlier, placing one near the sprinkler valve on the house side of the valve may solve the banging pipes problem by itself. His location is not subject to much freezing weather.

1 refrence to Florida's highest elevation
http://geology.com/state-high-points.shtml
2 reference to one of Washington State's hydro dams.
http://en.wikipedia.org/wiki/Grand_Coulee_Dam

Technician1002 wrote:Anti-water hammer air shocks have some limitations.

Air dissolves in water so unless the unit has a membrane they go flat. With a membrane, it needs periodic replacement as they fail over time.

They are designed to handle the spike near a faucet. They are NOT designed to prevent cavitation due to rapid shut off of flow into a long pipe. It may fail when subjected the vacuum of cavitation.

A Schrader valve allows you to replenish the air in the chamber every year or so.

IICRC 30 years ago, air-hammer chambers came with them.

My father owned a wholesale plumbing supply company.

A quick and dirty solution would be a PVC 'T' , a length of PVC, a cap with a hole in it, and a rubber tire Schrader valve pressed through it. (or copper)

I have tested pressed in Schrader valves to 600 psi.

Edit.. weird, my post just posted quotes not the post. Trying again.

Again on cavitation and water hammer. This is caused by the rapid shut off of a water source into a long pipe in many cases causing negative pressure and a large vacuum bubble which then collapses with a rush of water into the dead end.

Using a refillable air shock does not fix this as when the pressure goes negative, the air expands out of the stub and is lost downstream, then the stub fills with water instead of air.

Take a pipe at 4 bar. shut off the source and have the air shock go to .5 atm. The pipe volume expands 8X in volume. Most of the air is lost out to the system. Now it needs refilled after one arrest. As mentioned before the air shock are designed to take a pressure shock near a valve, not near a valve feeding a long pipe to solve vacuum cavitation. A vacuum break that lets in air would work better near the sprinkler valve along with the shock to prevent negative pressure. Properly placed the vacuum break can keep the shock filled with air.