Aerosol Correction Factors

Aerosol Generators

The nozzle pressure values below are used when substitute aerosol reagents are chosen rather than DOP and the aerosol output concentration of a Type III-A Laskin nozzle generator must be calculated.

Example:

  • DOP-20 psi applied with dilution airflow of 135 cfm yields 100 mg/m3
  • PAO-23 psi applied with dilution airflow of 135 cfm yields 100 mg/m3

13,500 X (# of nozzles in use) ÷ total filter airflow (CFM) = Aerosol concentration (mg/m3)

Note:    Adjustment of the nozzle pressure to accommodate the reagent in use is independent of the photometer internal reference reagent setting discussed below.

Aerosol Reagent Nozzle Pressure (PSI)
PAO-4 (CAS 68649-12-7 or 68037-01-4) 23
DOS/DEHS (CAS 122-62-3) 24.4
white mineral oil (CAS 8042-47-5) 22
polyethylene glycol (CAS 24322-68-3) 26.6
paraffin oil (CAS 8012-95-1) 24.2
corn oil (CAS 8001-30-7) 23.4

Aerosol Photometers

Photometer internal reference factors are multipliers used to adjust the reference setting required for a 100% reading.

They are only necessary when using an aerosol reagent that the photometer has not set up to use during factory calibration.

There are two examples that follow, one for analog and one for digital photometers.

Note:    Both Analog and Digital photometers apply the internal reference factor to the 100% reference value used for DOP.

Aerosol Reagent Internal Reference factor
DOP/DEHP (CAS 117-81-7) 1.00
PAO-4 (CAS 68649-12-7 or 68037-01-4) 0.73
DOS/DEHS (CAS 122-62-3) 0.96
White mineral oil (CAS 8042-47-5) 0.90
Polyethylene glycol (CAS 24322-68-3) 1.11
Paraffin oil (CAS 8012-95-1) 0.89
Corn oil (CAS 8001-30-7) 0.88

Example 1:          Analog series – TDA-2D, TDA-2E

  • DOP-10.0% setting required for 100% response to 100 mg/m3
  • PAO-7.3% setting (10.0% x 0.73 correction factor) required for 100% response to 100 mg/m3
  • DOS-9.6% setting (10.0% x 0.96 correction factor) required for 100% response to 100 mg/m3

Example 2:          Digital series – TDA-2G & 2H

  • DOP with P1 selected – 100 required for 100% response to 100 mg/m3
  • PAO with P2 selected – 100 required for 100% response to 100 mg/m3
  • DOS with P3 selected – 0.96 (0.96 X 100 DOP value) required for a 100% response to 100 mg/m3

Note:    The above correction factors apply only to air operated Laskin nozzle generators. If a thermal type generator (TDA-5A, TDA-5B or 5C) is used the upstream concentration MUST be sampled to obtain a 100% setting.