Earthquakes do occur from time to time on Dartmoor.
----------------------------------------------------------- Will (Haytor, Devon, 1017 feet asl)
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Obviously the earth moved for someone ....... :-)
- Tom.
They felt it in Bovey Tracey!
It was on the local BBC news.
2.7 on the Richter. They were all of a quiver.
Whilst on the subject, earthquakes of 3.5 - 4 on the richter scale are relatively common in west Cornwall, which is quite high be British standards. The epicentre typically just SW of Penzance. The last one in 1996 was 3.8 and did some limited damage (notably to the chuch at St. Levan, cracked windows etc, and broke one of my wine glasses!. Account at
Graham Penzance
Can't say I have noticed that many 4Ms on the NEIC lists or RedPuma (a repost site.) But a minimum of 4M is required for events outside the USA to make the list.
Anyone know anything about water hammer? (Jist fort I'd arsk.)
Anyone know anything about water hammer? (Jist fort I'd arsk.)
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It's the propagation of pressure waves in an enclosed water system (e.g. pipework) due to a sudden change in flow. It's normally caused by a sudden closure of a valve such as the toilet cistern or header tank. If one of those is the cause, fit slow-close valves. If it is a persistent problem, then it may be necessary to fit an expansion loop or shock arrester into the system. Short term cure - turn a tap on slightly to ease the pressure, and then close it slowly. If it's in the cold water rising main system, try turning the main stop c*ck (where the water enters the house) down slightly.
For more information, stick "water hammer" into Google.
jim, Northampton
I've been meaning to give that a go. I'd better do it before the plumbig goes tit's up in winter as it nearly did in that ice-frost last winter.
It is the mechanism Bernard Chouet uses to describe the harmonic of an open pipe in volcanic activity. But with a volcano giving long period harmonics similar to water hammer the volcano has to be closed.
Which is pretty much what occurs with hammering plumbing.
But how can any of it occur with the pipework or ducting sealed? If the presure is rattling, a seiche of some sort has to be open. Where is it coming from and where is it going to?
It occurred to me that with the OP's neck of the woods being the only hot water aquifer region in the UK, there might be some relationship with deep pressurised water... and the heat.
Well it had to come from somewhere, whichever mechanical geo- phenomenon you choose.
What sort of "hammer" are we talking about. A single bang when something shuts off too quickly or a drone/vibration when a cistern or tap is flowing?
The former is easy to ccure stop what ever is shutting off too quicj shutting off too quick. The latter can be a right bar stweard to sort out as it's all tied in with resonances, flow rate, valve seats etc.
But how can any of it occur with the pipework or ducting sealed? If the presure is rattling, a seiche of some sort has to be open. Where is it coming from and where is it going to?
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When you find out the answer, please be good enough to inform the hydraulics departments of all the universities around the world. The theory of water flow ranks alongside the creation of the universe in the great unsolved mysteries of our time debate.
jim, Northampton
Is that informed opinion or you just mouthing? If it is a mystery; how can several seeemingly sensible websites offer the same appeasement/take/sort-of-explanation, daft though they do appear to someone who is unaware of his own limitations according to some?
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