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Green 'O' Rings

I've just dismantled and re-assembled a big Grundfoss CR8 pump (1.1Kw

30 metre head 8 cu m/hr) to check the seals before putting it in service. (These are the main water pumps used in Launderettes). Seal kits from Grundfoss are ridiculously expensive - £115 plus VAT last time I bought one 3 years ago). The seal consists of a stationary ceramic face with a fat 'O' ring round the shaft squashed onto it with a spring and cup. The ceramic bit is sealed to the body by another 'O' ring, and both 'O' rings are green.

Often all that happens is that the 'O' ring rubs away to a flat face if the pump has run inadvertantly dry so replacement of the 'O' ring should restore a seal, but what is so special about GREEN ones ?

They are only pumping water, so no need for any chemical resistance, but I suppose the constant rubbing is rather adverse service conditions, although I do have one the has run trouble free 24/7 for 6 years (that's put a jinx on it!!)

AWEM

Reply to
Andrew Mawson
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Andrew, if its green than the odds are it is made of Polyurethane rather than rubber, and if this is the case it is for abrasion resistance. Polyurethane has probably the best abrasion resistance of any polymer, so would be useful in just the circumstances you describe. Regards

Peter

Reply to
Peter Neill

Hi Andrew

Bit of a old pump there! Grundfos have not been making CR8s for a few years now.

I have had a look at thier current catalogue and they refer to using "o" rings manufactured from EPDM or FKM in their current range of equivelant pumps. These CR pumps were originally design to operate with high temperature feed water, so possibly they used a green colour "o" ring to indicate it was for higher temperatures.

By the way no commention with Grundfos other than we use their pumps is some of our plants.

Have not yet used the casting boxes - have you got the generator cables and 415V plugs sorted out?

Cheers

Dave

Cheers

Reply to
Steam Train Dave

(1.1Kw

Hi Andrew

Bit of a old pump there! Grundfos have not been making CR8s for a few years now.

I have had a look at thier current catalogue and they refer to using "o" rings manufactured from EPDM or FKM in their current range of equivelant pumps. These CR pumps were originally design to operate with high temperature feed water, so possibly they used a green colour "o" ring to indicate it was for higher temperatures.

By the way no commention with Grundfos other than we use their pumps is some of our plants.

Have not yet used the casting boxes - have you got the generator cables and 415V plugs sorted out?

Cheers

Dave

Cheers

Dave,

Yes getting frighteningly close to firing things up. Working on the bulk water cooling at the moment (guess what - using a CR8 for circulation) but am still a bit stumped on the actual cooling side. Easy solution is a big tub of water as a heat sink but really I want a water to air solution like a fan assisted radiator (anyone got any old Myson fan assisted rads lying arround??) to avoid the bulk tank as space is limited.

BTW I just bought two CR8's on ebay, one brand new two stage made in

2002 which will be a launderette spare, and the other somewhat older three stage which is for induction furnace cooling duty !

AWEM

Reply to
Andrew Mawson

Good point there Dave. Polyurethane and EPDM only have recommended continuous use temperatures of around 80deg C, whereas FKM (or Viton as most will know it) has a continous use ceiling closer to 200deg C.

Peter

Reply to
Peter Neill

Patent rights held by Kermit, if you sniff them they smell of pork.

-- Regards,

John Stevenson Nottingham, England.

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Reply to
John Stevenson

Have a look at

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Mark

Reply to
mark

Install the discharge to the tub a few feet above the tub and fit a shower head/watering can rose to it. Either change the water every time you run or dose it with bleach to discourage legionella. Probably just drain down after every session to avoid growing rocks in it.

Mark Rand RTFM

Reply to
Mark Rand

A song by Booker T and the MGs?

Mark Rand (running) RTFM

Reply to
Mark Rand

Reply to
Andrew Bishop

ester and

Andrew,

Pump is back together so cannot measure - thanks for kind offer - I'll bear it in mind when it leaks in a week or two

AWEM

Reply to
Andrew Mawson

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