Decanting/ blending whip - I'm confused??

[Jen S]

Hi guys,

I'm looking at investing in a decanting whip, but after searching through some previous threads I'm now somewhat confused on the subject.

I hear talk of blending whips and decanting whips. Can someone explain the difference? I think I know, but just want to check my theory. Also, what is a bull nose fitting?

My plan is to use my single 12L as an o2 bank, for a bit of nitrox home brewing. The 12L is lying around doing nothing at the moment so might as well give it a job!

I've heard a lot of talk about the SAP whip - i've found this one:

5210Oxy Decant Assy Din/Gauge - B/Nose Ndl/V
Provides an inexpensive but accurate facility for partial pressure blending. See 'Good Ideas' suggestion.£284.35
(423.97

or this one:


1205G/NTXDin Cylinder Decant Assy Fitted Gauge (Nitrox/O2)
232 bar Cylinder Decanting Assy Fitted 63mm Dry Gauge & 50cm Hose For Nitrox/02 Use£135.01
(201.30 Euro

Will the £135 one work for my needs, as there's quite a difference in price!!

Or are there any others out there that people would recommend?

Thanks for you help,

Jen

[Fiona]

Jen

A bullnose fitting is what is used on O2 cylinders.

If you are decanting from dive cylinders you just need DIN on both ends as in the lower picture.

[Woz]

Answers below...

A bullnose connector is the fitting on a J cylinder.
The first SAP thingy you have there has a non-return valve and a needle valve in the hose, hence the price difference. The second one doesn't, so to control the flow of O2 the only thing you have to do this is the cylinder valve which on a standard cylinder valve is not the ideal bit of kit, as many internal bits of cylinder valves are not really made for throttling.

The cheapest way of getting a really accurate blending whip is to buy an AP valves O2 decanting hose with button gauge, the little bit that you screw into it so you can use it on DIN cylinders and then unscrew the button gauge and give it to me for being so nice and replace it with a standard SPG on a short 6" hose. The hose and SPG should be new and O2 clean. Alternatively get a Keller Eco1 digital gauge as this screws directly into the port.
I used my AP/Keller whip today to blend some 32% and some 50%.And I got 31.8% and 49.7% so I'm pretty happy. I used the cylinder valve on the J cylinder to control the flow to 6 bar/min which is handily 0.1 bar/sec which you can see ticking off on the digital gauge.

[finbar.taylor]

when blending you need a guage (both options have) and I would go for din to din as you can get an adaptor to bull nose if required but not other way round.

The only diference I really see is if you require a nedle valve on the whip. this allows for fine adjustment of the rate of flow between the 2 cylinders. This is not esential as you can use the tank valve but is not very acurate. I've managed OK using the valve on a J before but the results have not been as good as I would have liked but if you just doing your own then you have time which allows you to over come these problems anyway.

Fin

[Scuby]

The difference is usually in the valve and things to control it a little bit more finely.

Personally I use a simple DIN-DIN hose, with an SPG in the middle. Doing the same as you, mixing nitrox from a 12l which had nothing else to do. Was very useful when I used to live 45mins from the nearest shop that did nitrox, but where my club 10mins away had an air compressor. Doesn't get used much now that I have to get air from a shop anyway, and the shops almost all do nitrox too.

But anyway, I always found it perfectly fine to control the flow with the cylinder valves - although some valves are a bit crap, the ones on my cylinders allow very good control at low flow rates. I'd often leave it flowing very slowly for hours (while I did other things), rather than a very quick decant. Never out by more than 0.5%, usually a lot closer - there's probably more error in the analyser than the flow.

One thing to bear in mind with the decanting hoses if you're using high %O2 mixes is that the purge button on the hose can be very violent on some - the one i've got I can easily push down very slightly, and again that'll purge the hose nice and slowly (over several seconds).

David

[Woz]

Here's mine- the little shiny thing is the bullnose adapter and the 2 black things are the storage caps. The whole thing comes in at less than £200 for a digital setup.

[Jen S]

Woz,

That does look nice. Is the green knob bit the non-return/ needle valve? So it's basically like the first picture in my first post?

Also, Digger was on about something like this, but said you needed to put PTFE tape around the gauge to get it to fit - is that right as I'm not entirely sure about PTFE at 200bar??

Jen

[Woz]

1. PTFE tape perfectly fine at 200 bar. It's what they use to seal the valves of J cylinders with.
2. The gauge uses the identical thread to a scuba SPG- it even comes with the swivel and a 1/4" BSP adapter (which you don't need). You just unscrew the button gauge and screw in the Keller gauge. No PTFE tape needed, just the O ring from the button gauge.
3. The valve is for bleeding the hose down. You connect the gauge end to the O2 supply and t'other end to the cylinder. Control the pressure using the supply cylinder valve. When the required pressure is reached, turn off the supply cylinder valve, the cylinder valve and the hose valve. Purge the fitting that screws into the destination cylinder (just like a crack bottle DSMB cylinder- you get a pfffft). Then unscrew the fitting and open the green hose valve slowly to bleed the hose down nice and steadily. Of course you could also fit the bullnose to the other end and have the gauge next to the destination cylinder and use the hose valve as a needle valve. In fact that may be the better option.

[Woz]

To save me from replying to PM's the gauge is a 0-300 bar one of these:
KELLER Digital Manometer ECO 1
and is available in the UK from Omni Instruments.
You want the ECO1 0-300 bar with the additional rubber protective cover.
The decanting hose is an AP Valves AP8K with the DIN adapter (can't remember the product code for that).

Unfortunately although I have an account with Omni as I buy vibration monitoring equipment from them I don't get any discount on gauges so you are best off buying them yourselves.

[Ahmed Adly]

The first one you have in the picture is excellent. I used it for 5 years now in a commercial dive center filling nitrox and trimix.
I have an extra hose added, so I don't need to unscrew the thing for cascading.

The hose is of excellent qaulity and so is the guage and non returne valve.