SIP co2 disposable bottles

[HacksawParticipant @hacksaw]

I think i got hoodwinked today? Popped into Toolstation for a 600g disposable as they're cheapest in there…13 quid something..On the way out i noticed it's only 390g ! And no , it's not argon mix, just co2 .. I thought they were 600g? So i had a quick look in Halfords and their SIP co2 IS labled 600g , 14 quid, something !! However looking at Halfords website they advertise them as 390g ?. Perhaps old stock are 600 ? If they're in a plastic bag from elsewhere (SIP still ) it seems they're 600g though??

[HacksawParticipant @hacksaw]

[Ian ParkinParticipant @ianparkin39383]

Not sure about this but does the empty weigh 210gram

[peak4Participant @peak4]

Looks like SIP sell both 390g & 600g presumably designed specifically to catch the unwary.

Bill

[Speedy Builder5Participant @speedybuilder5]

And what can you make with the empty bottles. I have cut up a couple to make garden trowels – usual safety warnings etc.
BobH

[HacksawParticipant @hacksaw]

I made a rather heavy silencer for my mates ride on mower out of one.. it wont rot out in a hurry !

I'm going with Hobbyweld gas in future Dealer only 3 miles away

[Clive FosterParticipant @clivefoster55965]

When you sort out whats what properly best prices for 600 g ones seem to be around £20 – £21 and 390g around £13 – £14 (ish). Gas price is pretty much same at £ 3.50 (ish) per 100 g so it doesn't seem to matter much which you buy. That said you can pay nearly £20 for a 390 g one if you don't watch out.

Sealey do a 1 Kg re-fillable bottle. Retails around £10 to £15 empty and £80 – £90 odd full. Yikes thats over £7 for 100 g but re-fills (exhange) from local agents are said to be much less costly so "the investment is soon re-couped". Still a rip off deal to get a full one tho'. I have one and think re-fill price is now around £20 which is a bit better than disposables. 30 mile round trip either way so I've pretty much given up on MIG having a high end inverter stick welder that can go nearly as thin.

Clive.

[HacksawParticipant @hacksaw]

Local sealey dealer here is £35 or so for the 1 kg bottle and £ 12 for 1kg gas refill . Don't know if the £35 1 st payment includes gas though

[HacksawParticipant @hacksaw]

Ah ha ! Found something out today . SIP disposable Co2 only bottles …Grey bottles = 390g White bottles = 600g

[not done it yetParticipant @notdoneityet]

If you don't have a local sealy dealer, you might try a security/fire service or a pub landlord that will cut a deal.

[JuddyParticipant @juddy]

Machine mart retail a 600g bottle at about £14, **LINK** which has about 110L of gas content.

I use Adams gas hobby retail bottles  http://www.adamsgas.co.uk/product-category/hobby-welding-gas/ which are 9L 135 bar so about 1200L of gas which cost about £100 for the first one then about £30 for a refill dependant on the gas mix you want. These last me at my rate of use at least a year with no further cost (apart from the refill).

Buy the largest litre fill quantity i.e. capacity x pressure, to get the most gas as the disposable cylinders vary in pressure capacity.

Edited By Juddy on 21/07/2017 10:26:31

[MuzzerParticipant @muzzer]

With that said, bear in mind that the BOC Y-size is 5m3 and costs £42 inc vat to refill plus £45 inc vat a year rental, so if you plan to become any good at welding (you need to put in a lot of practice), you may be better off with a larger cylinder.

Murray

[not done it yetParticipant @notdoneityet]

a 600g bottle … has about 110L of gas content.

RMM of CO2 is 44 and applying Avogadro's Law and using the Molar Volume of 22.4l, 600 g of CO2 (13.6 Moles) would occupy about 300 litres at standard temperature and pressure. Even though CO2 is a vapour and not a gas a factor or 3 is a bit too far off the practical real value.

[JuddyParticipant @juddy]

The bottles state they contain 110L, the 600g must be the total weight.

[John Stevenson 1Participant @johnstevenson1]

Gas Direct at Newark

Can’t quote MiG as I only use full size bottles but 1/2 hight Oxy, about 3 foot tall and 6 to 8″ diameter costs 4.25 UKP per month rental, no up front charges. Refills are 7 UKP with a one off 10 UKP, per trip delivery charge.
All less Vat

MiG gas will be very similar on pricing so you have to do the sums over a period of time

[not done it yetParticipant @notdoneityet]

The bottles state they contain 110L, the 600g must be the total weight.

Nope. Can't see it. They do sell 390g ones, too, slightly cheaper. Other cannisters state volumes but the CO2 doesn't. At least not on their advert/catalogue. Please show me where it is stated and I will be very surprised. Ideal gas laws are only applicable to ideal gases (are there any?) but PV = nRT is a good approximation in most cases.

[JuddyParticipant @juddy]

Well, the cylinder I have in my hand states: tare 1100g, PH 165bar, maximum content 110L this is on the back of a 600g bottle, how this is measured by machine mart or any other supplier I've no idea. I would post a picture but I don't have the means.(this is on an old bottle brought some time ago, but does have both weight and volume)

I wouldn't want to purchase one these little cylinders with their small brass valve if it contained over 300 bar !!! This is a mystery, as you say the weight equates to a much larger volume of gas.

[SillyOldDufferModerator @sillyoldduffer]

There's something odd going on with these CO2 cylinders. When specified by weight, they are 390g or 600g. When specified by volume they are 60L and 110L. It's unusual for an advertiser to mention both weight and volume but I did find this example which says:

CO2 Gas Cylinder for Mig Welding / Fish tanks etc

390g / 60 ltr

'

As NDIY explains the weights and volumes don't match!

I wonder if it's to do with the temperature of the gas when the volume is measured. When CO2 emerges from a cylinder it is very cold. Perhaps they are giving the volume at this much lower temperature rather than at Standard Temperature? It's a mystery!

Could some kind soul weigh a cylinder before and after using it? If the weight labelling is accurate, an empty 390g cylinder should weigh 390g less than a full one.

Dave

 

 

Edited By SillyOldDuffer on 24/07/2017 09:53:46

[Clive FosterParticipant @clivefoster55965]

More gist for t'mill. Got a Maypole branded one says 450 g gas, average full weight 1660 g, test pressure 58 bar, burst pressure 200 bar.

According to Air Liquide **LINK**. 454 grams of CO2 takes up 0.447 litres at 300 psig / 21 bar and goes to 0.248 cubic metres / 248 litres at 70°F / 21° C.

So for practical purposes taking 450 grams as 250 litres is near enuf.

Pro rata its probably OK to say 390 grams goes to 215 litres and 600 grams goes to 330 litres.

The confusing thing about carbon dioxide is that below around 56° C and pressures over about 7 bar it becomes solid so you can't work directly work out volume from pressure and mass. The quoted pressures for the small cylinders is the working release pressure when there is somewhere for the gas to go as it sublimes out of the solid. Typically the disposable cylinders are specified to release gas at 35-36 bar. Obviously the cylinder has to be big enough to contain the specified mass of CO2 in liquid or solid form but given that the actual cylinder volume is only affects how much gas is left behind when pressure drops too low for the regulator to give the desired output. Larger cylinders have more gas left.

Clive.

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