Calibrating a Silca Floor Pump ?
Mike Pomrink
Calibration. The gage shows about 40 lbs. at all times. Pumping a tire up
to 110 (on the gauge) gives me an actual tire pressure of approximately
85-90 lbs. There are two brass screws under the clear cover. Are these
for calibration? Is there any trick for getting the clear cover off if I
need to adjust these screws?
Thanks
Mike Pomrink
Jobst Brandt
I don't know whether resetting the dial hand will make your gauge read
correctly, although this is what is often done. The dial pointer is
press fit onto the shaft and with care (or the correct tool) can be
pulled off and reinstalled to read zero.
What ruined your gauge is that someone tried to pump up a presta valve
without first depressing the valve plunger. Presta valves have a
conical fit seal that jams into its seat firmly enough to not pass air
even with the lock nut unscrewed. An attempt to free the valve by
pumping runs the hose pressure well over 200psi, something the gauge
does not accept without damage.
Jobst Brandt <jbr...@hpl.hp.com>
mrawl...@my-dejanews.com
"Mike Pomrink" <mpom...@philly.infi.net> wrote:
> I have a 20 year old Silca Floor Pump that is apparently out of
> Calibration. The gage shows about 40 lbs. at all times. Pumping a tire up
> to 110 (on the gauge) gives me an actual tire pressure of approximately
> 85-90 lbs. There are two brass screws under the clear cover. Are these
> for calibration? Is there any trick for getting the clear cover off if I
> need to adjust these screws?
>
>
> Mike Pomrink
> the brass screws hold the face plate on. the face plate is the area where the
numbers are printed. clear covers are held on by a number of ways by
different manufacturers....each has thier own.calibrations are performed
against a standard or known. cheap gauges are often calibrated against better
gauges. the calibration is pushing both the standard and the gauge to be
calibrated to the middle of the range and adjusting the needle ......by
removing it and replacing it at the proper point....then checking the high
value and zero. there is a tool for removing the needle. basicly cheap gauges
are easier to replace than calibrate unless you do that for a living.....i do
and if you would like i'll calibrate yours if you cover shipping. good luck
mike rawlings
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Richard McClary
He mentioned that if the presta valve sticks closed, the hose pressure
will exceed what the gauge can handle. This may ruin the gauge.
I have not only noticed this; it is a major irritation for me. Whenever
I try to top off my tire pressure, I need to release the valve (bleed
out a bit of pressure). Most of the time, the valve still sticks. I
need to remove the hose and bleed off pressure several times before the
blasted valve stays open to let me inflate.
Is this extremely common? Are there brands of tubes with valves less
sticky than others? Is this just a matter of the nature of my pump
(Topeak JoeBlow)? Something I live with?
Joshua_Putnam
>I have not only noticed this; it is a major irritation for me. Whenever
>I try to top off my tire pressure, I need to release the valve (bleed
>out a bit of pressure). Most of the time, the valve still sticks. I
>need to remove the hose and bleed off pressure several times before the
>blasted valve stays open to let me inflate.
>Is this extremely common? Are there brands of tubes with valves less
>sticky than others? Is this just a matter of the nature of my pump
>(Topeak JoeBlow)? Something I live with?
I've never needed to un-stick a valve more than once per
inflation. I'd check that nothing inside your pump chuck is
dragging on the side of the valve nut and jamming the valve
closed.
--
Jo...@WolfeNet.com is Joshua Putnam / P.O. Box 13220 / Burton, WA 98013
http://www.wolfenet.com/~josh/
Richard Watson
:>Jobst's reply to the pump gauge question has me wondering...
:>He mentioned that if the presta valve sticks closed, the hose pressure
:>will exceed what the gauge can handle. This may ruin the gauge.
:>I have not only noticed this; it is a major irritation for me. Whenever
:>I try to top off my tire pressure, I need to release the valve (bleed
:>out a bit of pressure). Most of the time, the valve still sticks. I
:>need to remove the hose and bleed off pressure several times before the
:>blasted valve stays open to let me inflate.
:>Is this extremely common? Are there brands of tubes with valves less
:>sticky than others? Is this just a matter of the nature of my pump
:>(Topeak JoeBlow)? Something I live with?
I find that even after the initial valve release I _sometimes_ get a little
``stickiness''. However this is never serious, and tends to take only about
120-130psi to free.
Richard
MSchadAPI
>for calibration?
No- these just hold the gauge to the body. If you open it up, you will see a
brass mechanism inside this consists of a hollow plenum that changes its shape
ir response to pressure. It is connected via arms to the needle. You could bend
this plenum, but the best way to calibrate is to just move the needle. I don't
know what you would calibrate it against though. Perhaps an air compressor with
a calibrated gauge? I've only ever moved the needle so it poits to zero with no
pressure.
MSchadAPI
>I try to top off my tire pressure, I need to release the valve (bleed
>out a bit of pressure). Most of the time, the valve still sticks.
Try spraying a bit of silicone into the valve. This has solved the problem for
me. I use Conti tubulars, which inflate to 170psi, so I know what you're
talking about
Walt Rauser
and that usually solves the problem. However, on occasion with a really
sticky valve, I have deflated the tire and put a drop of chain lubricant
into the valve. It never stuck again.
Walt
Richard Watson wrote:
>
> Richard McClary (rmcc...@napcc.aspca.org) wrote:
> :>Jobst's reply to the pump gauge question has me wondering...
>
> :>He mentioned that if the presta valve sticks closed, the hose pressure
> :>will exceed what the gauge can handle. This may ruin the gauge.
>
> :>I have not only noticed this; it is a major irritation for me. Whenever
> :>I try to top off my tire pressure, I need to release the valve (bleed
Jobst Brandt
> I alway tap the valve stem with the pump head before attaching the
> pump and that usually solves the problem. However, on occasion with
> a really sticky valve, I have deflated the tire and put a drop of
> chain lubricant into the valve. It never stuck again.
Don't do this with latex tubes. A little oil will go a long way in
dissolving the latex tube... pssssssss s s s s s s s s s
Jobst Brandt <jbr...@hpl.hp.com>
Wheelaholic
jbr...@hpl.hp.com (Jobst Brandt) wrote:
> Walt Rauser writes:
>
> > I alway tap the valve stem with the pump head before attaching the
> > pump and that usually solves the problem. However, on occasion with
> > a really sticky valve, I have deflated the tire and put a drop of
> > chain lubricant into the valve. It never stuck again.
>
Jobst Brandt writes:
> Don't do this with latex tubes. A little oil will go a long way in
> dissolving the latex tube... pssssssss s s s s s s s s s
Aaahhh. Thanks for confirming my suspicion. I was wondering why my tubes were
developing holes over the nipple holes despite the use of relatively new rim
tape. I had oiled the spoke nipples (rather excessively) when trueing my
wheels(with the help of Jobst's book!). Some of the oil soaked into the rim
tape where the spoke holes are. Then, after a day or two, I'd hear the
dreaded psssss... Fortunately both times it happened I was not on the road.
Being suspicious of the oil, I cleaned the rim and replaced the rim tape and
tube. No more tires mysteriously deflating.
Cheers,
Nicholas
(Adelaide, South Australia)
THolland63
> I have a 20 year old Silca Floor Pump that is
> apparently out of Calibration.
You can get a new gauge, an Ametek P500K-200CBM, from Grainger for less than
$10.
TRH