Small slit nitrogen wiv braze

[gwm121]

Standard nitrogen cylinder is heavy and unwieldy to use while brazing small splits. Gauges need constant readjustment for the minisicule flow required..

We are looking at using an old r22 dumpy 9kg bottle with a bespoke small regulator designed for very low flow. Anyone else tried this? Anyone found a quick easy way to get very low flow needing little adjustment ?
What pressure did you fill r22 dumpy to for max duration?
Anyone come across a quick way to connect to ¼ 3/8 ½ 5/8 copper as required?

2. Sometimes there are only two brazes on a single split installation and these real difficult to set up. Its tempting not to use nitrogen, however having had a modern electronic refridgerent flow valve apart it looks as though even the smallest contaminant could cause a problem. There are inline gauze filters on these. Your opinions valued folks…. (leave out the warranty issue, we are looking at the level of risk for malfunction over life of unit on a difficult setup with limited number brazes on the odd occcasion..as allways one callback or malfunction completely negates saving couple hours time…)

[Rob White]

.

There are two parts to this, the practical bit and then the sensible bit.

I'll do the practical bit first.

Just do the maths.

A small OFN cylinder is charged at 200 bar, you have a
small dumpy and it's max pressure would be less than 30 bar.

If you filled it to 20 bar for safety sake.

If the cylinder is 10 Kg, that's about 10 litres, 10 ltr X 20 bar
is about 200 ltr. Your flow rate should be at 1 bar - 2 ltr a minute.

200/2 = 100 mins, allowing for losses and and irregularities that could
be reduced to 60 mins.

60 mins is a reasonable amount of time and should be long enough for a
small split.

Now the sensible bit.

Do not under any circumstances use a cylinder for something it is not designed for.
Do not under any circumstance adapt or adjust a regulator or valve and never use
them for something that they are not designed for..

Regards

Rob

.

[Grizzly]

The nitrogen bottles are like that for a reason.
Irrespective of size they have to be able to withstand something like 3000 psi of standing charge.
If you decant into another cylinder, you could inadvertently pressurise that cylinder to those sort of pressures.

Don't go there the chances of this going wrong well outway the inconvenience of using the proper kit.
There are small manageable cylinders out there just check out the suppliers.
Besides which it's a bad option you are considering with all the liability on whoever does it!
Grizzly

[gwm121]

Thank you for first reply, absolutely helpful, we were looking at around 200psi and vey useful calculation of volume available.
and for second reply... did not know one could obtain tiny nitrogen cylinders and is now being ordered so no need struggle with a dumpy.

nb. decanting into dumpy r22 cylinder wouldnt have been a problem using nitro regulator set at 200psi (hundred) and aircon guages, and as first reply could have been a viable option. thank you.

[Grizzly]

nb. decanting into dumpy r22 cylinder wouldnt have been a problem using nitro regulator set at 200psi (hundred) and aircon guages, and as first reply could have been a viable option. thank you.
That's what I used to think as well, until it was explained to me how the regulators work and they can malfunction.
Which is another reason for the advise given.
Glad to assist!
Good Luck.
Grizzly.

[monkey spanners]

Excuse the messy shed,

https://www.youtube.com/watch?v=TlkhTHXS7NY

[cadwaladr]

There are some crazy people in our industry?

[MikeHolm]

Yup, one of them likes farming and one big old silly looking diesel truck (and making videos):D:D

[glenn1340]

Use a flow meter combined with a two stage regulator. Manifold gauges are hopeless for controlling a very low flow:
http://www.amazon.co.uk/Turbo-Torch-0386-0849-Nfm-Tt-Nitrogen/dp/B0076O41IK

As they say on the BBC: other flow regulators are available

[Grizzly]

Use a flow meter combined with a two stage regulator. Manifold gauges are hopeless for controlling a very low flow:
http://www.amazon.co.uk/Turbo-Torch-0386-0849-Nfm-Tt-Nitrogen/dp/B0076O41IK

As they say on the BBC: other flow regulators are available
And as Amazon Say "Currently Unavailable"!
Grizzly