Frequently Asked Questions about the Frazier Differential Pressure Air Permeability Instrument

Frazier Air Permeability - Main Page

Where can I get replacement calibration charts for the Frazier Air Permeability Tester?

Where Can I get User Manuals for Air Permeability Instrument?

Can the ranges of the Air Permeability Tester be extended?

What are the differences between the Frazier Air Permeability Tester Models FAP-F2, FAP-HP, FAP-LP, FAP-F2AR?

Explain the Calibration of the Air Permeability Instrument.

What are the Air Permeability Test Plates?

What are the Initial Set-up procedures for the Air Permeability Instrument?

What are the normal maintenance procedures for the Air Permeability Instrument?

What are the operation procedures for the High Pressure Air Permeability Instrument?

What are the operation procedures for the Low Pressure Air Permeability Instrument?

What is the Frazier Number?

Size of Unit

Standard Units used by Frazier Air Permeability Testers

Conversion of Standard Units used by Frazier Air Permeability Testers

 

Extending Ranges of Permeability Tester:

Yes - contact us for an explanation

Replacement Calibration Charts:

Contact us with the Serial Number of your instrument

Air Permeability Instrument Calibration:

The Frazier Differential Pressure Air Permeability Instruments are calibrated in accordance with the calibration procedure originally developed by the National Institute of Standards and Technology using equipment checked and calibrated by them.  We follow this procedure in general but have changed it somewhat so that theory agrees with our experience under actual use conditions. In addition, we adjust each instrument to be identical as possible to our Master Instrument and, as a consequence, all previous instruments. Most of the calibration of these instruments reside in the individual calibrated venturi nozzles that are supplied as standard equipment to the instrument. This calibration is permanent and intrinsic to the nozzles and should not change over time through use of the instrument unless the nozzles are abused or neglected.

A test plate is supplied as standard equipment to check the actual operational performance of the instrument and the specific calibration of the 4mm nozzle.  Other test plates are now available as optional equipment to check the calibration of the other nozzles. These test plates cannot be used to adjust the instruments or calibrate the nozzles.

Your test plate should agree within +/- 2% with the above calibration when used on your instrument or any other Frazier Air Permeability Instrument.  The reading that you actually obtain with the above test plate on your instrument should be repeatable within +/- 1% on your instrument over an extended period of time.  Any abrupt departure (more than 2%) from your reading or a slow change over time will indicate that either your instrument's operational performance has degraded, the calibration of the test plate has changed, or the calibration of the nozzle (hence the instrument) has changed.

You cannot recalibrate the instrument yourself.  Recalibration can only be done at our facility.  Any adjustment (other than cleaning) that is made by the owner of the instrument will probably only make the problem worse.  In most cases proper cleaning will solve the problem (see maintenance instructions).

The Frazier Differential Pressure Air Permeability Instrument, its operation, and calibration is described in the National Bureau of Standards Research Paper RP 1471 pages 637 to 642.

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.

 

 

 

Air Permeability Test Plates & Test Plate Calibration:

Because of the increasingly stringent needs of our customers for a means of checking  the calibration of their Frazier Differential Pressure Air Permeability instruments as demanded by laboratory calibration authorities, Frazier Company has agreed to produce a series of test plates for checking the calibration of our instruments.

The calibration of the Frazier Differential Pressure Air Permeability Machines is intrinsic in the Calibrated Venturi Nozzles that it uses to measure air flow.  Once each of the nozzles is calibrated, that calibration is permanent and is not affected by use of the instrument.  Only actual physical abuse of the nozzles themselves such as dirt, scratches, nicks, corrosion, etc. will affect their calibration.

The instrument itself can be caused to malfunction through abuse or age.  However, these malfunctions are easily reversible.  Some conditions that can cause the instrument to malfunction include oil in the system, air leaks in the system, aged or improper oil, improper leveling of the instrument, obstructions in the system and malfunction of the electrical components.  All of these problems are easily repairable by the owner.

The standard test plate provided with each instrument should be used, on a regular basis, to check the system to ascertain if the instrument is operating properly.  It cannot be used to adjust the instrument or affect the calibration which is intrinsic to the nozzles.  The test plates function by simulating a relatively unchanging test sample.  The nozzles themselves can only be calibrated or recalibrated by Frazier Company at our production facility.

As a general guide, under good condition, a reading obtained when a test plate is used should be within plus/minus 3% of the test plate calibration.  However, a variation in reading within plus/minus 2% is preferred.  A variation in readings of up to about plus/minus 1.5% due to changes in atmospheric density is normal in addition to the above.  A reading discrepancy of more than plus/minus 5% is usually unacceptable.  Variations of plus/minus 5% can occur when the nozzle is not calibrated in the instrument in which it is to be used.  This tendency to larger error is especially true when a nozzle is used in a non-standard instrument or a test plate is used to check non Frazier Instruments in which case larger variations can be expected.

The standard test plate can also be used to check the calibration of the 4 mm nozzle to ascertain if it has been subject to abuse or has become dirty. 

Because the standard test plate only can be used to check the calibration of the 4 mm nozzles, and because of the increasingly more demanding needs of our customers, Frazier Instrument Company has developed and is selling a special series of test plates that can check the calibration of the other eight nozzles that are standard with our instruments.  These test plates also cannot be used to adjust the instrument or calibrate it or calibrate the nozzles.

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.

Explanation of the Frazier Number:                                                                    

The Frazier Differential Pressure Air Permeability Instrument has been the standard in the industry for measuring air permeability for many years.  The term “Frazier Number” (or CFM as some people refer to the number as) has developed over the years in regard to permeability or porosity because of popularity of the this Instrument.  People actually use this term with different definitions depending on the application, so therefore what one company or industry may call the Frazier Number may mean something different to another.  Because of the multiple industries that use the instrument, strictly speaking there is no specific definition.  In some cases people will use the Frazier Number to describe airflow but not give the differential pressure at which the airflow was taken.  Usually in these cases the differential pressure is set to 0.5 inches of water due to industry standards but this is not always the case.  In other cases, people will use the results given by the instrument but will have modified the test sample opening size and therefore have a repeatable number but will no correlate with the standard one square foot of sample area. 

The Frazier Differential Pressure Air Permeability Instrument’s permeability readings are “rates of flow of air in cubic feet per square foot of sample area per minute.”  Therefore many, but not every time, when someone mentions a “Frazier number” (or in some cases CFM) it is most likely this specific reading at a differential pressure of 0.5 inches of water as the commonly set variable.

Many times a Frazier Air Permeability Instrument out in the field is simply referred to as a “Frazier”.  There are other permeability instruments however, and you must be careful as they do not necessarily correlate with the Frazier even though they may be called a “Frazier” type permeability instrument. 

Our instruments are very reliable and have a very good repeatability of readings even from instrument to instrument and location to location.  This is what people have come to expect when referring to the “Frazier” in testing air permeability.

Size of Unit:  

Unit is located in a table that is 48" Wide by 24" Deep by 31" High.  Overall size of High Pressure Unit (FAP-HP) and Frazier 2000 Unit (FAP-F2)  is 57" High and Low Pressure Unit (FAP-LP) is 49" High.  Actual working apparatus can be removed from table and installed in a manufacturing line or on a lab bench.

Standard Units used by Frazier Air Permeability Testers

1.  Standard units for this tester are: differential pressure (inches of water); air flow (cubic feet per square foot of sample per min).

2.  These standard units are converted automatically to any type of pressure and air flow units with FAP-F2A (Frazier 2000) and FAP-F2AR (Frazier 2000 Retrofit).  Conversion charts can be created for FAP-LP (Low Pressure) and FAP-HP (High Pressure) by using Frazier 2000 software or automatic conversion of units can be accomplished when using Frazier 2000 software with FAP-LP and FAP-HP.

3.  Differential Pressure Number is generally set by industry standard or industry organization.  Most air permeability testing is done at 0.5 inches of water (example - ASTM D737, ASTM F778, ASTM C522).

4.  Air Flow Number results from testing the sample at a given Differential Pressure Number.

Conversion of Standard Units used by Frazier Air Permeability Testers

Standard units are converted automatically to any type of pressure and air flow units with FAP-F2A (Frazier 2000) and FAP-F2AR (Frazier 2000 Retrofit).  Conversion charts can be created for FAP-LP (Low Pressure) and FAP-HP (High Pressure) by using Frazier 2000 software or automatic conversion of units can be accomplished when using Frazier 2000 software with FAP-LP and FAP-HP.

Units can be manually converted using the following conversion factors:

Differential Pressure or Pressure Drop - (inches of water)

  1. (inches of water) x 0.0833 = (feet of water)
  2. (inches of water) x 25.4 = (millimeters of water)
  3. (inches of water) x 2.54 = (centimeters of water)
  4. (inches of water) x 0.254 = (decimeters of water)
  5. (inches of water) x 0.0254 = (meters of water)
  6. (inches of water) x 0.0024582 = (physical atmosphere (atm))
  7. (inches of water) x 0.0025399 = (technical atmosphere)
  8. (inches of water) x 0.073554 = (inches of mercury)
  9. (inches of water) x 1.8683 = (millimeters of mercury (torr))
  10. (inches of water) x 0.036126 = (pounds per square inch (psi))
  11. (inches of water) x 5.2022 = (pounds per square foot (psf))
  12. (inches of water) x 25.399 = (kilograms per square meter)
  13. (inches of water) x 0.0025399 = (kilograms per square centimeter)
  14. (inches of water) x 249.08 = (pascals (Pa) or (newtons per square meter))
  15. (inches of water) x 0.24908 = (kilopascals (kPa))
  16. (inches of water) x 2.4908 = (milibars)
  17. (inches of water) x 0.0024908 = (bars)

Air Flow - (cubic feet per square feet of sample per minute) or (feet per minute) or (CFM)

  1. (CFM) x 0.3048 = (cubic meters per square meter of sample per minute) or (meters per minute)
  2. (CFM) x 0.00508 = (cubic meters per square meter of sample per second) or (meters per second)
  3. (CFM) x 30.48 = (cubic centimeters per square centimeter of sample per minute) or (centimeters per minute)
  4. (CFM) x 0.508 = (cubic centimeters per square centimeter of sample per second) or (centimeters per second)
  5. (CFM) x 3.048 = (cubic decimeters per square decimeter of sample per minute) or (liters per square decimeter of sample per minute) or (decimeters per minute)
  6. (CFM) x 0.0508 = (cubic decimeters per square decimeter of sample per second) or (liters per square decimeter of sample per second) or (decimeters per second)
  7. (CFM) x 18.288 = (cubic meters per square meter of sample per hour) or (meters per hour)
  8. (CFM) x 5.08 = (cubic decimeters per square meter of sample per second) or (liters per square meter of sample per second)