Identifying a filtration unit

[steveharriss]

Can anyone identify the manufacturer of this particular filtration unit please?

http://www.yupp.co.uk/C.jpg
http://www.yupp.co.uk/D.jpg

TIA

[windy]

The tower is a old type used by SAS Ltd
Spares and carts can be got from
Bauer kompressoren uk 01942270771
From the stickers and other parts on your system.
i think its been to either hamworthy or central compressors at some time.

[Phil Laughton]

The tower is a old type used by SAS Ltd
Spares and carts can be got from
Bauer kompressoren uk 01942270771
From the stickers and other parts on your system.
i think its been to either hamworthy or central compressors at some time.

It could be a Bentley filter but it's not one I would touch. I doubt if anyone would test this tower as it has a fitting in the wall, a weak point.

Phil

[iain/hsm]

Steve.
It looks an odd little set up, any chance of a wider picture?
The steel fittings rusting into the aluminium tube won’t have done the alloy threads in the filter shell much good.
Also the steel taper fittings into the aluminium look like they are in all the way, too deep. The valve (top right) is that a taper thread or as I suspect a MDE on/off pull to bleed with a parallel thread with the parallel valve jammed into a taper hole in the filter shell with enough turns just to get the outlet position orientation. Can’t think why, maybe someone’s idea of a back pressure regulator.
Do filter shells this small need a hydro as the nick in the side wall could cause you problems. A new filter that size is about £180.00.
My guess is SAS Wigan now Bauer made the Alloy shell, MDE the valves and Bristol Pneumatics now Hamworthy provided the sticker. Iain

[steveharriss]

Well here are some more photos.

Compressor Equipment - a set on Flickr

If anyone is able to help with the best course of action but I thinking that a replacement filtration unit is probably the best option?

So recommendations please.

[iain/hsm]

Great photos I think I can guess what was trying to be done here. They were using the small silver tower as a secondary filter for double filtering. The MDE on/off pull to bleed valve in the top right of the filter tower would have been used not as a back pressure regulator but as a method to reduce the flow through such a small filter.

HP air direct from the compressor would be at say 5 to 18scfm and would first go through its own filter on the compressor before this panel and to this secondary filter. So originally the flow rate could never be above the rated capacity of the pump. Granted with the secondary filter when downstream of the compressor it also cannot flow more than the compressor but as it’s so small a larger flow will or would have overwhelmed the filter chemical. Frankly it would not have been much if any use.

However if you look on the panel there is a small yellow handled valve, I guess this is the line from the HP air storage bank. (and please NOT an oxygen line)
If that’s the case HP air from the storage bank could flow many hundreds of times faster than the compressor ever could, hence the MDE valve was fitted to act as a crude flow control throttle.

The pressure gauge is upstream of the check valve so it can only show the filter pressure not the scuba bottle pressure or the filling rate.

To be honest IMHO it is a poor inadequate job the installer clearly knew not nearly enough to undertake this sort of work. I would look also very closely at the rest of the system.

Filter flow capacity is a combination of filter chemical diameter by filter length, the larger the diameter the slower the flow, the longer the filter bed the greater the adsorbtion capacity. Both these factors together are also known as “dwell time” but it also requires a known back pressure and the chemical type and mesh size to work dwell time out properly.

My guess this secondary filter came off an old scrap air compressor and someone was duped into thinking it would make an adequate secondary filter suitable for nitrox.

You know by simply turning on the filter bank valve then opening the MDE inlet valve to this filter with the downstream MDE valve closed or even the scuba bottles closed my guess is we could create enough adabatic compression heat to make a small fire in the filter chemical especially if the filter medium is charcoal and the flow direction is the same as MDE use in there filters. Shall I bring sausages LOL ?

[steveharriss]

Oooh err. That doesn't sound great! How do I go about sorting this particular mess then? Be gentle with me please!

[iain/hsm]

For starters one item that I thought most compressor operators used to reduce flow in a filter stack is a “frit”. It’s a small HP fitting with a precision hole or orifice in it that is small enough to reduce the flow downstream of it and in stainless steel at £12.00 it’s cheaper than a valve.

They are also used as a cheap method to connect HP gas to a LP analysers again not needing a regulator £50.00 and relief valve £30.00 and a 0-5 l/min inline flowmeter £30.00 and a valve £20.00. Total cost £130.00 or:

The £12.00 “frit” slows the flow and pressure of say a 300 barg bank down to say 2 l/min for an analyser with just a 0.7mm hole.

Granted a "frit" for a compressor filter would have to be calculated for say 12acfm or 300 l/min flow but no matter how big the bank size is the frit would always control the flow by the size of hole. To prevent the frit from blocking a simple inline 2 mu (micron) stainless filter can be used at £30.

[iain/hsm]

Another small point.
The frit would be fitted to the inlet side of the filter not the outlet that way you save yourself from blasting the heck out of the chemical cartridge when you open the bank to filter valve.

A BPR or back pressure regulator (also called a priority valve) is what you fit to the outlet side of the filter tower in order to build up pressure inside the chemical stack before allowing the gas out of the filter and into the charging scuba line. This is to "thicken" up the gas. Air at 200 to 300 bar is like treacle. Try a pot dive blow down >60MSW 7 bar ATA on He BIBS, then take a breath of the chamber air its like breathing by swallowing its so thick.

Also in the filter as the gas is so “thick” the water vapour and long chain hydrocarbons in the gas stream cannot pass around the chemical matrix so get adsorbed into the chemical as the water and oil are non compressible.

The BPR needs only about 180 to 200 barg to really have an effect in knocking out the oil and water vapour. The more this pressure is increased the lower the humidity or water vapour. Say at a setting of 100 bar and you get a –40C dewpoint reading, by increasing the BPR pressure say to 200 bar you would see this approaching –60C dewpoint, giving even dryer gas.

However the kicker is that the higher the BPR pressure setting the shorter the chemical life. Its a trade off.

[Phil Laughton]

I agree with Iain, this system seem to be a total lash up and you would be better off starting from scratch. The only thing I would save is the pressure regulating valve mounted in the centre of the panel. The pipe work and fittings look poor, so I think you will have to bite the bullet and spend some money to upgrade the whole system.
For new filters and other parts you should look at the MDE web site and the SAP web site for parts such as the inline restrictors and filters. MDE also supply chargeing clamps with a pull dump and pressure gauge, DIN or A fitting.

Phil