Auto changeover valve for twin LPG bottles

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lxsw20

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#1964144 25-Feb-2018 23:04

The easy option is to just have one bottle turned off, then you turn it on manually when the first bottle empties out and order another one.

gregmcc

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#1964163 26-Feb-2018 04:27

Aredwood: I'm on holiday currently using some flaky mobile data. So I'm not going to try and lookup some very large PDF files right now.

But you would sure hope that a reed switch that was installed in the regulator by the manufacturer would be safe. All of the reed switches I have seen have the switch contacts contained in a glass cylinder, which would avoid any leaking gas from being able to reach the contacts. And assuming the reed switch is connected to a Arduino GPIO pin. There would only be 2.5mW of electrical energy flowing through the switch anyway. (will check later if this is even enough energy to be able to light an air gas mixture)

Or you could just install the regulator so it is out of the clearance zone.

Doesn't quite work like that, the regulator will always be within the zone as it's part of the gas system, and anything electrical within the zone must meet specific hazardous area requirements, I doubt that an Arduino has the required certification

chevrolux

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#1964608 26-Feb-2018 15:36

Didn't even really think about the spark potential. Makes sense I suppose, but sure these days valves with electronics would be more common place.

Thanks @Aredwood for the lead - will chat with the local plumber and see what he reckons. In my mind the valve simply gets installed, we run some bog standard wire to it (probably just cheap speaker cable, or alarm PIR cable) and put that on to an Arduino. Most probably use ESP8266 as I bought a whole handful to make multisensors and could apply the same script with MQTT to handle the switching event.

I can see what paying are saying about sparks but surely a valve with a reed switch built in has the correct fittings to terminate a cable on the contacts?

gregmcc

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#1964656 26-Feb-2018 16:57

chevrolux:

Didn't even really think about the spark potential. Makes sense I suppose, but sure these days valves with electronics would be more common place.

Thanks @Aredwood for the lead - will chat with the local plumber and see what he reckons. In my mind the valve simply gets installed, we run some bog standard wire to it (probably just cheap speaker cable, or alarm PIR cable) and put that on to an Arduino. Most probably use ESP8266 as I bought a whole handful to make multisensors and could apply the same script with MQTT to handle the switching event.

I can see what paying are saying about sparks but surely a valve with a reed switch built in has the correct fittings to terminate a cable on the contacts?

It's all about the energy potential to ignite the gas been available. anything in a potential explosive atmosphere (within a certain area around the gas bottles) has to be as either intrinsically safe (not enough energy to ignite the gas) or in a suitable hazardous area enclosure that meets the requirements of the zoning.

A home brew arduino would not be able to meet those requirements, maybe by feeding the reed switch through the right type of Intrinsically Safe barrier (it's and electronic device) you may be able to meet the requirements, but remember to legally do this (and more importantly safely) you need to be a Registered Electrician with recognised competency in hazardous area electrical work.

I would recommend that you engage a professional as you are messing with both gas and electricity both of which you need to be legally registered to work with.

chevrolux

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#1964699 26-Feb-2018 17:42

gregmcc:

chevrolux:

Didn't even really think about the spark potential. Makes sense I suppose, but sure these days valves with electronics would be more common place.

Thanks @Aredwood for the lead - will chat with the local plumber and see what he reckons. In my mind the valve simply gets installed, we run some bog standard wire to it (probably just cheap speaker cable, or alarm PIR cable) and put that on to an Arduino. Most probably use ESP8266 as I bought a whole handful to make multisensors and could apply the same script with MQTT to handle the switching event.

I can see what paying are saying about sparks but surely a valve with a reed switch built in has the correct fittings to terminate a cable on the contacts?

It's all about the energy potential to ignite the gas been available. anything in a potential explosive atmosphere (within a certain area around the gas bottles) has to be as either intrinsically safe (not enough energy to ignite the gas) or in a suitable hazardous area enclosure that meets the requirements of the zoning.

A home brew arduino would not be able to meet those requirements, maybe by feeding the reed switch through the right type of Intrinsically Safe barrier (it's and electronic device) you may be able to meet the requirements, but remember to legally do this (and more importantly safely) you need to be a Registered Electrician with recognised competency in hazardous area electrical work.

I would recommend that you engage a professional as you are messing with both gas and electricity both of which you need to be legally registered to work with.

yep can totally understand that!

I wouldn't touch any thing gas related anyway - sometimes I can barely put a fitting on a tap properly without it leaking haha.

My thought would be that valve with the switch is the only thing in the vicinity of the bottles, the arduino would be off somewhere else - maybe inside the garage or back in the comms cupboard even.

InstallerUFB

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#1964883 27-Feb-2018 08:51

Quick image of some of the exclusion zones that are now required for any Chorus Network open transition points (copper or fibre) - in compliance with building regulations

gregmcc

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#1965226 27-Feb-2018 16:16

InstallerUFB:

Quick image of some of the exclusion zones that are now required for any Chorus Network open transition points (copper or fibre) - in compliance with building regulations

Looks very similar to what is in AS/NZS3000

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andrewNZ

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#1965333 27-Feb-2018 18:43

In Dunedin there are loads of installs of auto changeover bottles. They appear totally mechanical.

Don't have one in this place so I can't give you a brand, but I Rembert them working well except in cold weather when the butane wasn't gasifying properly and manual switching was needed.

Mavarick

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#1966066 28-Feb-2018 19:23

Funny about this topic, Genesis just sent a reminder in the mail about how to use this type of set up :)

geoffwnz

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#1971969 9-Mar-2018 15:40

lxsw20:

The easy option is to just have one bottle turned off, then you turn it on manually when the first bottle empties out and order another one.

This is my method also. There's a very distinct indicator when the shower goes cold, usually just after applying shampoo. :-p

The auto changeover valve works in that it will switch from the current primary bottle to the secondary one when the primary drops below whatever the threshold is. But as someone else noted, there seems to be some level of backflow into the primary bottle after that, so the easiest solution seemed to be to keep the secondary bottle off until primary is empty, then close primary, open secondary, resume shower.
Plus it saves remembering to check the valve periodically.

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robertsona

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#2023986 28-May-2018 15:04

The auto changeover valve works in that it will switch from the current primary bottle to the secondary one when the primary drops below whatever the threshold is. But as someone else noted, there seems to be some level of backflow into the primary bottle after that, so the easiest solution seemed to be to keep the secondary bottle off until primary is empty, then close primary, open secondary, resume shower.
Plus it saves remembering to check the valve periodically.

We're experiencing issues with our two cylinder setup and I'm uncertain what is going on. Would appreciate any advice.

Our LPG is supplied by Genesis. Until recently, Genesis contracted the LPG supply to Elgas and everything worked well with the autochangeover system - seamless operation. However, Genesis now have their own LPG supply operation and now when a new cylinder is delivered, they are leaving its valve closed. The first time they did this, they left a pre-printed note saying it was for safety reasons. Several times now we have run out of hot water - indicated by cold showers - and most annoyingly having to relight the pilot light.

This is the bit that gets me: when the the changeover valve (presumably) flicks over to the newer (still shut) cylinder, and I then open that valve, there is a sound of backflow to the older empty cylinder - is this normal or is it indicative of some failure in the changeover mechanism?

Should I just open the valve of the newer cylinder immediately after delivery?

And why would the deliverers leave it shut anyway? Is this happening for other Genesis LPG customers?

geoffwnz

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#2023993 28-May-2018 15:15

robertsona:

The auto changeover valve works in that it will switch from the current primary bottle to the secondary one when the primary drops below whatever the threshold is. But as someone else noted, there seems to be some level of backflow into the primary bottle after that, so the easiest solution seemed to be to keep the secondary bottle off until primary is empty, then close primary, open secondary, resume shower.
Plus it saves remembering to check the valve periodically.

We're experiencing issues with our two cylinder setup and I'm uncertain what is going on. Would appreciate any advice.

Our LPG is supplied by Genesis. Until recently, Genesis contracted the LPG supply to Elgas and everything worked well with the autochangeover system - seamless operation. However, Genesis now have their own LPG supply operation and now when a new cylinder is delivered, they are leaving its valve closed. The first time they did this, they left a pre-printed note saying it was for safety reasons. Several times now we have run out of hot water - indicated by cold showers - and most annoyingly having to relight the pilot light.

This is the bit that gets me: when the the changeover valve (presumably) flicks over to the newer (still shut) cylinder, and I then open that valve, there is a sound of backflow to the older empty cylinder - is this normal or is it indicative of some failure in the changeover mechanism?

Should I just open the valve of the newer cylinder immediately after delivery?

And why would the deliverers leave it shut anyway? Is this happening for other Genesis LPG customers?

I would recommend closing the empty cylinder *before* you open the new one if you are going to stick with only keeping one on at a time.
Both open is supposedly quite ok and allows the auto changeover vale to work seamlessly. But you will need to monitor regularly so you don't end up running both out.

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Ge0rge

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#2024006 28-May-2018 15:48

At the last place I lived, we purchased the two cylinders outright. It was cheaper than renting them for the amount of gas we went through. It did mean we had to take them in to be filled, not that that was a drama with a ute. We left both cylinders open when connected, and would pop past the bottles every now and then to check if the red flag was showing.

I guess a major advantage of this was we only paid for the gas we were using. I personally never noticed any backflow when changing cylinders over - just the obvious sounds of the line up to the regulator charging when the new cylinder was turned on. However if there was any, it wouldn't matter as the tanks were only being topped up as opposed to being replaced completely- we only paid for the gas put into the cylinder, not a default fee regardless of actual gas volume provided by the bottle rental places.

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