SNGB submersible pump fault

[abowie]

. Any thoughts?

That will work; IP58 rated gland seal. Shouldn't need any sealant.
In 20 years of cave and deep wreck diving I have made and maintained a lot of equipment that needs to keep water away from electronics. These are what we generally use. Your local electrical supply house will have ones made of brass or stainless as well. You may need metal rather than plastic to get the thread tight enough to seal around the top plate. You will probably be able to get one with the correct thread so you can use the original nut off your old pump for authenticity.

[Heuer]

Thanks Andrew. I will see if I can find a metal version in preference to the plastic or Petro Patch solution but if the latter works it would be good for those people who already have the pump and may not yet understand the problem. A quick fix that could be done with the pump in situ.

[PeterCrespin]

Pete - not sure you could use water as a test liquid given Petrol has an SG of 0.737 and is more likely to find its way through crevices, I assume. Petrol's volatility is what causes a full tank to 'pressurise' speeding up the leak.

Yes it wouldn't be perfect but it would be safe :-). I was thinking of a mild pressure test David, not just gravity or capillary action. There would presumably be a time constraint on any testing and a quick pressurization check would show up weepng.

Vented tanks, meanwhile, don't pressurize of course. Vapour pressure is a physical constant and for petroleum is well below atmospheric, hence its volatility.

[Heuer]

Well the Petro Patch was not a success:


It did not want to stick to the brass, rubber or heat shrink.

Found a supplier of nylon cable glands: http://www.mossexpress.co.uk/nylon-cabl ... tAodr3gA9g
Brass IP68 cable glands: http://www.caledonian-cables.com/produc ... lands.html
Hazardous use cable glands: http://www.caledonian-cables.com/produc ... lands.html

So the question is - are the Polyamide - 6, Neoprene and Perbunan seals fuel safe

[PeterCrespin]

Neoprene is oil & petrol resistant rubber and polyamide is what the white fuel line is made of - probably the black compression fitting (?) too. Dunno about the third one as I've never heard of it. Might be a trade name rather than generic?

Pete

[Heuer]

Perbunan?

"Perbunan? represents a range of oil-resistant acrylonitrile-butadiene rubbers (NBR) with a particularly high level of quality and properties. The product range includes grades with 18 to 45% acrylonitrile content and Mooney viscosity from 30 to 125. With Perbunan?, it is possible to obtain oil-resistant vulcanizates that can resist extremely low temperatures. In comparison with vulcanizates based on other NBRs, Perbunan vulcanizates show clearly better physical properties, heat aging resistance and abrasion and wear behavior. For the manufacturer of rubber articles, an important feature of Perbunan? is its vulcanization behavior. Perbunan? compounds are fast-curing, a property that contributes to an improvement in productivity.

Perbunan? can look back on a long history. It was developed by Bayer in the 1930s as the first-ever oil-resistant rubber. Since then there have been several "modernizing" improvements and today it is manufactured according to principles that take into consideration not only the good physiological properties of the rubber but also protection of the environment.

Perbunan? is recommended for many technical rubber articles. Perbunan? is the first choice for oil seals. Here, the "second generation" Perbunan? grades were developed to allow consistent and trouble-free production.

A series of special applications in the automotive and construction industries would not be possible without Perbunan?. For example, applications in the automotive industry, where the maximum operating temperature does not substantially exceed 120?C, are oil filter seals, torsional vibration dampeners, membranes, membranes in fuel injection systems, fuel and oil pipes, hose in hydraulic systems. In machines and installations, Perbunan? is used in all sorts of static and dynamic seals, from O-rings to complicated shaft seals, in heat exchanger seals, in pressure hose, rolls and drive belts. Perbunan? is a possible base material for articles for food contact applications such as milking inflation tubes, aerosol seals and food-carrying hoses.

Key Properties

- very good resistance to oils, greases and fuels
- very good low temperature flexibility
- good physical properties (modulus, compression set)
- good resistance to aging
- high resistance to wear
- low gas permeability"

This looks to be the kind of thing that is required:

[Heuer]

Just received my submersible pump back from SNGB following its modification and testing:


They have made three changes. The green nylon filter has been replaced with a brass sieve to improve flow, a new gland fitting has been sourced and the cable exit has been sealed:



I will install it over the weekend and give it a test. Many thanks to Julian and the guys at SNGB for working through the problem so diligently and coming up with an improved design so quickly.

[abowie]

Can you ask Julian if he plans to offer the upgrades, or at least the gland, to other purchasers?
I bought mine a couple of months ago and have been reassured in a one line email that min "is fine" however I have lingering doubts.
AS yet it remains unfitted as I'm still reassembling my car.

[stef]

I finally got my car back on the road and filled it up.

Sure enough, there is a lot of fuel leaking out around the power cable.

I have contacted SNGB and am waiting for an answer.

[abowie]

When did you buy your pump?

[stef]

I bought my pump on Aug 18, 2013

[abowie]

That's interesting as that's about when I got mine, which I am assured is ok.

[Heuer]

Mine is now leak free. Maybe SNGB should do a recall?

[stef]

Definitely. It is not terribly safe having petrol pouring out of the tank.

Lets hope everybody who bought one are aware of the problem. I would hate to hear of somebody getting hurt or killed because his E-type blew up.

[Heuer]

The scary bit is opening an electric garage door or switching on a light with that much petrol vapour in the air. I shudder to think what would have happened if the central heating in our garage had been switched to timed rather than 'off' when mine leaked.

It would be irresponsible of SNGB not to at least send a letter to everyone who purchased a submersible pump warning them of the problem and also offering a modified unit. As they are aware of the problem they are liable if anything serious happened I presume?

[Heuer]

That's interesting as that's about when I got mine, which I am assured is ok.

Andrew

I was assured my replacement pump would be OK as it was completely checked over and adjusted by the SNGB expert - it leaked just as bad as the first one

[stef]

Alex at SNGB sent me a new pump on my report of the problem.

It arrived yesterday and is the same type as David's modified version.

I have installed it and filled up the tank.

No leaks, so all good sofar. Hopefully the sealant around the cable is of the lasting type.

[andrewh]

Just fitting my sngb submersible pump and was wondering what are the correct fixings? Are they a slot head pan screw or a small hex? Anyone know the thread size as well?

[Heuer]

Eight setscrews UFS.119/4R and eight copper washers AW.102/E. There is the gasket as well obviously #C17504 and worth fitting a new one. Try filling the tank to the brim and check it every hour or so for leaks.

[Dave K]

I have had my SNGB pump for around 7 years, I did notice that the filter gauze was looking a bit worse for wear when I pulled it out of the tank last year. Is the new type filter available to purchase separately? I also noticed on mine that there is a smell of fuel if I fill the tank right up so I never fill it right up anymore. The smell is only noticeable when the boot lid is opened with a full tank, you wouldn't smell it if the boot was shut and you walked into the garage.

Dave