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Hello all,
DaviesCraig responded to my inquiry today, saying that there is hardly any resistance to flow while the pump is off, and that a series setup is a solution they think will work well. Their exact response is below, but what it basically means is that no valves and plumbing complications are required - just pass the flow from one to the other, and you can run either pump, or both.
This device is looking better every day!
Oh, and yes, the all-caps was their idea, not mine. =)
Regards,
Chad
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DEAR CHAD,
Thanks for your email and Davies, Craig EWP enquiry.
----- Original Message -----
From: "Robinson, Chad" <crobinson@rfgonline.com>
To: <dcfans@daviescraig.com.au>
Sent: Sunday, October 12, 2003 12:53 AM
Subject: EWP - backflow?
Some fellows and I are discussing the use of this pump in an area where
redundancy is preferable. I can't seem to find information on your site
regarding backflow in the event the pump is not operating. That is, what
resistance to flow exists if the pump is off? HARDLY ANY ESPECIALLY IN
COMPARISON TO THE RESISTANCE TO FLOW OF A RADIATOR TUBE. IF YOU HAVE A EWP
YOU CAN LOOK INTO THE INLET AND SEE THE SIZE OF THE OPENING PAST THE
IMPELLER AND INTO THE OUTLET.
If it is low, we would need a check valve, but if it is high we might get
away without one. Also, if it is VERY low, we might put the pumps in series.
PUMPS IN SERIES SOUNDS LIKE THE ANSWER
In this second case, the goal would be to provide additional flow during
times that require high cooling, or if the first pump fails. How does this
pump handle flow above its design limit? NO TROUBLE - WE HAE MANY EWPs
INSTALLED AS A BOOSTER TO THE ORIGINAL BELT DRIVE MECHANICAL PUMP . HERE IS
OUR TECHNICAL BULLETIN ON THIS SUBJECT.
EWP TECHNICAL BULLETINS
EWP AS A BOOSTER PUMP
What a lot of our customers in your situation have done with great success
is add the EWP (part no 8005) into the lower radiator hose, wired direct to
the battery via an on/off thermal switch (part no 0401) and use the EWP as a
booster pump.
Both the existing belt driven mechanical pump and the EWP will pump through
each other when running alone and they will boost each other when running at
the same time. In fact, when running together they will pump more than the
sum of the two, pumping alone.
You set the temp switch to the temp below which you want the engine to run.
If the temp goes above that set temp, the EWP will turn on and run until the
engine temp is 4 degrees C cooler and switch off.
When you turn off a hot engine, the heat in the exhaust manifold passes to
the block and the engine temp actually increases after you turn off the
engine. If the head is alloy and the block iron, they will expand at
different rates and the head will tend to twist to accommodate the
difference, then the head gasket will be damaged.
Being wired direct to the battery, when you turn off a hot engine, the EWP
will run and wash out heat soak until the engine temp reaches the set temp
less 4c. After the EWP turns off, the heat may still transfer and the EWP
will turn on for another short period. The EWP may run for about 4 minutes
all up and at 6 amps there will be very little drain on the battery.
This will eliminate heat soak and the engine damage associated with it.
MOUNT THE EWP IN THE LOWER RADIATOR HOSE IS BEST
Does it provide impetus, or will it cap off at a certain limit (or worse,
overspeed?). That could make putting them in series a bad idea. I AM NOT
SURE JUST EXACTLY WHAT YOUR APPLICATION IS SO IT IS DIFFICULT FOR ME TO
COMMENT ON THIS.
Regards,
Richard Davies
Managing Director
Davies, Craig Pty. Ltd.
PLEASE NOTE : WE HAVE MOVED TO
77 TARAS AVENUE, BOX 363
ALTONA NORTH, VICTORIA , 3025
AUSTRALIA
TEL: +61 (0) 3 9369 1234 FAX 9369 3456
WEB page www.daviescraig.com.au
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