Re: Green 'O' Rings


"Steam Train Dave" <davidi1107@xxxxxxxxxxx> wrote in message
news:1150214512.774286.213020@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

Andrew Mawson wrote:
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

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


.

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