Head Office:

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Orifice Plate Field Test of Water Ring Vacuum
Pumps
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Tel [phone] Fax 886 3
4526227,4511347 E-mail sales_at_cutes.com.tw Web
site www.cutes.com.tw
Head Office No. 2-22, Nan Yuan Road, Chung Li
City, (320) Taiwan, R.O.C
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1. What is orifice plate field test.
Using a simply flat of orifice plate to test the
vacuum pump on site. Simply and easy to get the
vacuum pumps performance curve to help the
customer decided to keep running, repaired,
rebuilt or change to new pump.
2. What you should prepare before field
test. 2-1. Adequate orifice plate. 2-2. Rubber
stopper. 2-3. Vacuum gage(more accuracy is more
better). 2-4. Tachometer(to test vacuum pump
really rpm). 2-5. Test record table.
3. Field test procedure
3-1. Fill out the Field test record sheet. 3-2.
Determine which type of test should be
performed(single plate, dual plate) .Make sure
the correct test plate(s) and correct size
stoppers are available.
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3-3. Inspect for debris clogging and clean is
necessary. a. Pump inlet. b. seal water
piping. c. gauge taps. d. discharge separator
drain. 3-4. Clean pump inlet flanges and spray
lubricant on each to seal from leak. Place
rubber gaskets and the specified orifice plates
onto pump inlet flanges(as drawing) 3-5. Install
vacuum gauges into tapped holes in inlet heads(as
drawing)
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3-6. Install any type of thermometer or
temperature gauge in or on seal water supply
piping to measure the seal water temperature
during the test. 3-7. Be prepared to measure
pumps RPM. 3-8. Open seal water supply valve and
assure that there is adequate flow to the
pump. 3-9. With all orifice holes open, start the
pump. 3-10. Until the vacuum at stabilize vacuum
level. 3-11. Record the number of orifice hole
open(for each plate), the vacuum level(at each
inlet for dual plate test), the seal water
temperature and motor current. NOTE For dual
plate test, be sure to always have equal number
of stoppers in each orifice plate when taking
reading. 3-12. Install one stopper into orifice
plate(s) then read the number of orifice holes
open, the vacuum level and motor current then
record this. 3-13. Repeat 3-12 until only one
orifice hole is open or reach the rating current
of motor. 3-14. Record the barometer , ambient
temperature and seal water temperature. 3-15.
Take RPM reading and record(very important).
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Orifice Plates for field tests
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4. Convert raw data to corrected test ACFM (Total
ACFM Tested).
a. Convert tested vacuum levels for barometer and
record as corrected vacuum levels.
Corrected Vac. test vacuum(inHgV) x 29.92 /
Barometer(inHgA)
b. Refer to the attached air flow chart to
determine pump test capacity. The chart shows
the flow rate through one orifice opening at the
particular corrected vacuum reading(ACFM/Orifice).
c. Find out the seal water correction factor
from its attached chart. d. Correct for ambient
air temperature.
Amb. Air C.F. 460 Ambient Temp. (F) / 520
e. Multiply No. of orifice open by
ACFM/Orifice by Seal water correction factor
by Ambient air C.F. to determine the total
ACFM tested
NOTE For dual plate test, the No. of orifice sum
both side.