Low Pressure Frazier Air Permeability Instrument Instructions for Set-up and Operation

The Frazier Differential Pressure Instruments are built into a table and are shipped completely assembled and calibrated.

The procedures for preparing them for use is as follows:

            1.  Uncrate the instrument by carefully removing the wood crate and inner paper cover.  Keep in mind that the instrument contains delicate exposed glass tubes.

            2.  Lift the table containing the instrument off of the crate base and place it where it will be used.

            3.  Verify that the variable transformer indicates "0" and switch is in the off position and plug the instrument into an appropriate electrical outlet.  Make sure that the transformer reads "0" before you start any procedure.  This is very important.

            4.  Level the instrument by means of the leveler screws under each table leg.  The table should be roughly leveled in this way and then precisely leveled according to the built in bubble level. In the Low Pressure Instrument this is accomplished by means of the two thumbscrews under the inclined manometer.   The Bubble Level itself should never be moved or adjusted or the instrument will be caused to become out of calibration.  The built in bubble level is used solely to indicate the correct slant of the inclined manometer.  This level should never be adjusted.  Adjustment of the level itself will destroy the calibration of the instrument. It must be returned to the factory for recalibration if the level is disturbed.

            5.  Since your instrument is a Low Pressure Air Permeability Instrument one manometer reservoir can  is on the right side of the table and the other is part of the inclined manometer assembly which is attached to the backboard.  The filler hole for the inclined manometer is next to the large adjusting knob on the right side. This filler hole has to be closed tightly to avoid air leakage.  Add the proper Red Oil - specific gravity 0.827  (included in the shipment) to the two manometers until they read zero.   Be sure not to overfill above the zero mark.

            6.  Clamp the 4 mm standard test plate on the top of the 2 3/4 inch diameter test opening on the top of the table (where the samples are normally tested) and screw the 4 mm nozzle into the chamber below the table.  Note:  The Test Plate is not a calibration plate and it cannot be used to calibrate your instrument.    The door should then be latched closed firmly, but it need not be air tight.

            The transformer switch should then be placed in the "on" position and its knob should slowly be rotated to increase the speed of the blower.  Watch the oil in the inclined (left hand) manometer being pulled back.  (Be sure to proceed carefully so as to not run the oil over the top of the manometer.  Adjust the speed of the motor until the inclined manometer reads 0.5" of water (The instrument reads in inches of water even though oil is in the manometer.)

            Observe the position of the red oil in the vertical (right hand) manometer.  This reading of the vertical (right hand) manometer should then be noted. The corresponding air flow in terms of Cubic Feet per Minute should be taken from the 4 mm column of the proper calibration chart.  For example, if the elevation of the red oil is at the 10" line then the air flow is        (read from calibration chart)          cubic feet of air per square foot of material.   Most likely the reading will not be a whole inch such as given in the calibration chart.  Air flow at the 1/10 of an inch can be computed from the calibration chart by doing a straight interpolation between the whole inches given.  For example the air flow for 10.5 should be assumed to be halfway between the reading for the 10" and the  11" on the calibration chart. The value of your specific test plate given on the calibration chart is       (read from test plate card)        C.F.M., so the oil should be approximately on the       (interpolated from calibration chart)       line.

            If you obtain substantially the same reading as the actual calibration shown on the card that was included with the Test Plate, you can be confident that the instrument is working correctly.  This reading should be repeatable for years.  If you obtain a significant variation either the calibration of the test plate or nozzle (or both) has changed or the instrument itself is not in good operating order.  The most common reason why the instrument would not be operating properly is that oil has been drawn into the system through operator error.  Other special test plates are available to check the calibration of each of the other nozzles.  See the "Test Plates and Calibration" FAQ.

            7.  Samples are tested by the same procedure as per 6 above.  (A test plate represents an unchanging sample).  However the operator should be alert, especially when testing unknown samples, not to increase the speed of the blower to the extent that one or the other of the manometers has oil pulled into the system.  Please note that oil in the two manometers does not move at the same speed.  This movement varies with the sample tested. Extreme caution should be taken.  If oil is pulled into the system (e.g.. the oil disappearing over the top of the glass tubes or beyond the highest available reading) the instrument will not read correctly until the oil is completely cleaned out.  Please see the "Maintenance Instructions"  Since oil in the system is always due to operator error and it is the most common problem, please note that it is not covered by the warranty.

            8.  The size of the nozzle you use in testing depends on the porosity of the material under test.  The greater the porosity the greater the opening of the nozzle.  But at all times the nozzle should be small enough that the red oil of the vertical manometer reaches at least the 3" line.  (The machine is not as accurate below the 3" line.)

            9.  May we add that the Test Plate (See "Test Plates and Calibration") is supplied  for detecting malfunctions of the machine, caused by oil in the system (accidental overflow of the red oil into the copper connecting tubes), air leakage through the filler plug of the right hand oil reservoir.  In this case a thorough cleaning of these tubes with a cleaning fluid, such as Acetone becomes necessary.  (See "Maintenance Instructions") The Test Plate cannot be used to calibrate your instrument, although it can be used to verify the calibration of the instrument.

We recommend that Test Plates be recalibrated yearly by Frazier Company due to possible changes through handling over time.

Yearly calibration is also a partial requirement for ISO certification.