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UK diy (uk.d-i-y) For the discussion of all topics related to diy (do-it-yourself) in the UK. All levels of experience and proficency are welcome to join in to ask questions or offer solutions. |
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#1
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Soft close solenoid valve for DIY fox scarer?
I finished making my fox (and cat) scarer using one of those noisy impulse water sprinklers. This is controlled by a PIR which activates a 12v solenoid valve connected to the garden hose that then connects to the sprinkler.
It works a real treat but the problem is that solenoid slams shut instantaneously. This sends a shock wave back through the water system. And the result was that the shock waves caused a water leak at a junction of the incoming water supply from the street. My question is to find out if there's an easy way to overcome the shock wave problem - either by:- 1. Electrical solution to close the solenoid progressively - whilst still making it open instantly. or 2. Some mechanical means in a pressure vessel or whatever? All suggestions are welcome. |
#3
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Soft close solenoid valve for DIY fox scarer?
On Tue, 23 Oct 2012 11:54:00 +0100
Harry Bloomfield wrote: presented the following explanation : I finished making my fox (and cat) scarer using one of those noisy impulse water sprinklers. This is controlled by a PIR which activates a 12v solenoid valve connected to the garden hose that then connects to the sprinkler. I tested that idea around 20 years ago :-) I gave the idea up simply because our water pressure was not sufficient to provide a jet of water quickly enough on the opening of the solenoid. One solution to the shock, might be to T in a length of hose pipe between solenoid and water supply. If the new length of pipe were maintained full of air, then because the air is and the hose are compressible, it would act as a buffer to the shock. That is a perfectly sound idea, used in industry as well as some domestic situations. I have seen it in a basement at the utility sink. I once had the same problem with a four-inch water supply pipe, which descended vertically from a plant ceiling for more than 40 feet before meeting a solenoid valve. The resulting shock made the pipe's horizontal run, before the change to the vertical, move a foot sideways at its worst. We tried these shock absorbers, but they weren't man enough for this job. It was fixed by installing a slow stepping valve, at the top of the vertical drop, which was slow enough to gradually control the water flowrate. Getting up to the valve was an experience in itself. -- Davey. |
#4
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Soft close solenoid valve for DIY fox scarer?
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#5
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Soft close solenoid valve for DIY fox scarer?
In article ,
writes I finished making my fox (and cat) scarer using one of those noisy impulse water sprinklers. This is controlled by a PIR which activates a 12v solenoid valve connected to the garden hose that then connects to the sprinkler. It works a real treat but the problem is that solenoid slams shut instantaneously. This sends a shock wave back through the water system. And the result was that the shock waves caused a water leak at a junction of the incoming water supply from the street. If, as you say, the shock is causing a leak in your domestic supply pipework (not your hose or hose fittings) then your pipework or that of your supplier is faulty. Solution, fix it, or have them fix theirs. My question is to find out if there's an easy way to overcome the shock wave problem - either by:- 1. Electrical solution to close the solenoid progressively - whilst still making it open instantly. or 2. Some mechanical means in a pressure vessel or whatever? All suggestions are welcome. If you are talking about the shock affecting the hose fittings then the following may help: By nature, solenoids are bangy, they operate with more and more force as they close so it is an inherent problem. You can get slow close solenoid operated valves for irrigation but they are a bit slow in operation so I doubt they would be suitable. You can get shock arrestor capsules (similar to expansion vessels) for use on water systems. See water hammer arrester half way down this page: http://www.bes.co.uk/products/109.asp The inverted pipe idea wont work long term as the air will be re-absorbed by water under pressure. -- fred it's a ba-na-na . . . . |
#6
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Soft close solenoid valve for DIY fox scarer?
On Tuesday, October 23, 2012 11:28:40 AM UTC+1, wrote:
I finished making my fox (and cat) scarer using one of those noisy impulse water sprinklers. This is controlled by a PIR which activates a 12v solenoid valve connected to the garden hose that then connects to the sprinkler.. It works a real treat but the problem is that solenoid slams shut instantaneously. This sends a shock wave back through the water system. And the result was that the shock waves caused a water leak at a junction of the incoming water supply from the street. My question is to find out if there's an easy way to overcome the shock wave problem - either by:- 1. Electrical solution to close the solenoid progressively - whilst still making it open instantly. or 2. Some mechanical means in a pressure vessel or whatever? All suggestions are welcome. Oil the solenoid. Try 20/50 first. NT |
#7
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Soft close solenoid valve for DIY fox scarer?
On Oct 23, 11:28*am, wrote:
I finished making my fox (and cat) scarer using one of those noisy impulse water sprinklers. This is controlled by a PIR which *activates a 12v solenoid valve connected to the garden hose that then connects to the sprinkler. It works a real treat but the problem is that *solenoid slams shut instantaneously. This sends a shock wave back through the water system. And the result was that the shock waves caused a water leak at a junction of the incoming water supply from the street. My question is to find out if there's an easy way to overcome the shock wave problem - either by:- 1. Electrical solution to close the solenoid progressively *- whilst still making it open instantly. or 2. Some mechanical means in a pressure vessel or whatever? All suggestions are welcome. http://en.wikipedia.org/wiki/Water_h...ating_measures |
#8
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Soft close solenoid valve for DIY fox scarer?
Grimly Curmudgeon wrote:
On Tue, 23 Oct 2012 03:28:39 -0700 (PDT), wrote: My question is to find out if there's an easy way to overcome the shock wave problem - either by:- 1. Electrical solution to close the solenoid progressively - whilst still making it open instantly. or 2. Some mechanical means in a pressure vessel or whatever? All suggestions are welcome. Insert a T-piece with a blanked vertical pipe from it of around a foot length of 1" pipe. Leave it filled with air. It will act as a shock absorber. Until the air dissolves. |
#9
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Soft close solenoid valve for DIY fox scarer?
On Tuesday, October 23, 2012 11:28:40 AM UTC+1, wrote:
You can get slow-closing solenoid valve for this application. You could also use a solenoid valvle as a pilot valve operating a diaphragm valve, with a restriction in the diaphragm discharge; I can't recall how that's done now. Many large 'solenoid' valves are pilot operated diaphragm valves. Plan B, get a motorized ball valve; less likely the stick open than a solenoid. |
#10
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Soft close solenoid valve for DIY fox scarer?
Onetap wrote:
On Tuesday, October 23, 2012 11:28:40 AM UTC+1, wrote: You can get slow-closing solenoid valve for this application. You could also use a solenoid valvle as a pilot valve operating a diaphragm valve, with a restriction in the diaphragm discharge; I can't recall how that's done now. Many large 'solenoid' valves are pilot operated diaphragm valves. Plan B, get a motorized ball valve; less likely the stick open than a solenoid. Make sure it can handle the pressure. |
#11
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Soft close solenoid valve for DIY fox scarer?
It works a real treat but the problem is that solenoid slams shut instantaneously. This sends a shock wave back through the water system. And the result was that the shock waves caused a water leak at a junction of the incoming water supply from the street. As others have said, if the water hammer is enough to separate a joint to the main pipe in the street, then it should have blown the hozelok fittings off the hose feeding the solenoid as well or before the street joint failed, same if the hose was jubilee clipped on etc, so basically the street joint was about to give way anyway, could have happened next time you flushed the bog and it's valve shut off abruptly, or you closed the kitchen tap fast enough, or the washing machine/dish washer's solenoid did the exact same thing the fox scarer's solenoid does. I bought a cat/fox/dog/pikey sprayer from maplins for £14 a few months ago, runs on 4 x AA's, Comprises of a spike, an infrared detector and an impulse sprinkler head... all plastic of course, so a 6 volt solenoid inside it, Simple to use, push the spike in the ground, put in the batteries, connect the hose pipe to the hozelok connection on the side, set up the sensitivity of the detector to cover the area you want to spray, then adjust how far round the sprinkler works in the 'dut-dut-dut-dut' phase before hitting the trip to make it go 'zzyyyppppp' back to the beginning, Then call the Gf out of the house so she walks in front of it and tests it for you I've had it on the front garden for about 4 months now, batteries are still fine in it, but the bloody cat that ****s on the lawn still hasnt learnt, it gets a soaking every couple of days, so after i take it in for winter, i'll prolly cannibalize it and make an automatic dog waterer (replacing the sprinkler head with a hose that lets the water out gently for her to drink when she approaches... save her begging for someone to turn the wall tap on for her all the time in summer... hopefully. |
#12
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Soft close solenoid valve for DIY fox scarer?
On Tue, 23 Oct 2012 20:21:58 +0100, "Doctor Drivel"
wrote: Insert a T-piece with a blanked vertical pipe from it of around a foot length of 1" pipe. Leave it filled with air. It will act as a shock absorber. Until the air dissolves. So put a Schraeder valve on top. |
#13
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Soft close solenoid valve for DIY fox scarer?
On Wednesday, October 24, 2012 11:58:28 AM UTC+1, Gazz wrote:
As others have said, if the water hammer is enough to separate a joint to the main pipe in the street, then it should have blown the hozelok fittings off the hose feeding the solenoid as well or before the street joint failed, The others is wrong. You can get a huge shock pressure from water hammer. There have been many accidents where water hammer has smashed steel pipe fittings, usually slugs of condensate on starting a steam main from cold. It's how a hydraulic ram works. |
#14
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Soft close solenoid valve for DIY fox scarer?
Grimly Curmudgeon wrote:
On Tue, 23 Oct 2012 20:21:58 +0100, "Doctor Drivel" wrote: Insert a T-piece with a blanked vertical pipe from it of around a foot length of 1" pipe. Leave it filled with air. It will act as a shock absorber. Until the air dissolves. So put a Schraeder valve on top. Oh my God, he wants to pump it up every few weeks. |
#15
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Soft close solenoid valve for DIY fox scarer?
On Wednesday, 24 October 2012 12:34:22 UTC+1, Onetap wrote:
It's how a hydraulic ram works. No, if you have water hammer, your hydraulic ram stops working. An effective ram relies on the air spring, and in getting nearly all the energy of the ram into that air spring, from where it can then be usefully made use of. All water hammer does is to make your valves bounce. (And unlike you, I've built rams, and they worked) |
#16
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Soft close solenoid valve for DIY fox scarer?
On Wed, 24 Oct 2012 18:01:24 +0100, "Doctor Drivel"
wrote: So put a Schraeder valve on top. Oh my God, he wants to pump it up every few weeks. Well, you have to do something to while away the idle hours. You could draw on your experience with pump-up penile insertions. |
#17
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Soft close solenoid valve for DIY fox scarer?
On Sun, 28 Oct 2012 19:45:15 -0000, "Doctor Drivel"
wrote: How does your work? And again, in Engilsh? |
#18
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Soft close solenoid valve for DIY fox scarer?
On Wednesday, October 24, 2012 9:50:53 PM UTC+1, Andy Dingley wrote:
No, if you have water hammer, your hydraulic ram stops working. An effective ram relies on the air spring, and in getting nearly all the energy of the ram into that air spring, from where it can then be usefully made use of.. All water hammer does is to make your valves bounce. (And unlike you, I've built rams, and they worked) How does it generate a higher pressure pulse than the pressure of the water stream? By bringing the water stream to a sudden halt and converting the kinetic energy into pressure. And what is this effect called? Water hammer. http://en.wikipedia.org/wiki/Water_hammer#Applications "The water hammer principle can be used to create a simple water pump called a hydraulic ram." http://en.wikipedia.org/wiki/Hydraulic_ram "The device uses the water hammer effect to develop pressure that allows a portion of the input water that powers the pump to be lifted to a point higher than where the water originally started." Unlike you I am neither a patronizing dullard nor wrong. I shall expect your apology shortly after you grow a spine. |
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