Most Government agencies and departments are changing from DOP to 4 cSt polyalphaolefin (PAO-4) because DOP has listed on the suspected carcinogen list.
Since Dr. Hugh Carlon of the Army Chemical Center has completed research on Emery 3004 (PAO-4), the Surgeon General has accepted PAO as an acceptable substitute for DOP in the U.S. Army. The Department of Energy and their various test sites, along with the Food and Drug Administration, are also accepting PAO as a replacement for DOP. Research conducted by the Army Chemical Center and Dr. Hugh Carlon has also shown that PAO is safe.
To convert TDA-4 series or TDA-6 series Generators from DOP to PAO:
- Drain the existing DOP liquid from the unit
- Fill the reservoir to approximately half way on the sight gauge with PAO liquid
- Briefly operate the unit as normal to purge the nozzles of existing liquid.
- Drain the reservoir to eliminate any residue DOP remaining in the reservoir
- Refill the reservoir to approximately half way on the sight gauge with PAO
- Operate the unit as normal.
Correction Factors (Analog units)
As long as systems are tested using ratiometric mode (100% upstream aerosol sampled), no adjustments are required.
Adjustment will be required in situations where three (3) conditions exist:
- The photometer used for detection is calibrated to DOP
- The generator contains PAO
- The use of the Internal Reference is necessary.
The reason for this is that PAO has a different refractive index and gives a more intense photometric response than DOP. Therefore, a factor (of DOP) must be incorporated to insure accuracy if an upstream aerosol sample cannot be obtained to establish a 100% baseline and an Internal Reference for DOP must be used with some other liquid in the generator. Please see FAQ046 for more details.