Process flow time, especially on volume production, is reduced.
The emulsifiable mixture is easily removed from complex shaped parts, making it advantageous for use
on threads and keyways.
a. The variables associated with controlling emulsifier dwell time are eliminated.
Disadvantages Of Water Washable Penetrant, Method A.
a. There is no control over the diffusion or emulsified layer. Penetrant entrapped in flaws contains
emulsifying agent, making it susceptible to removal by over-washing. It is also easily removed from
broad, shallow flaws.
b. Water rinse time is critical and must be carefully controlled.
c. Residual background is higher than that from the same sensitivity level postemulsifiable penetrant
d. The penetrant emulsifying agent mixture is susceptible to water contamination.
e. Treatment/disposal of large quantities of rinse water contaminated with water washable penetrant.
Water Washing or Spray Rinsing.
Water washing or spray rinsing is usually accomplished in a stationary rinse tank, which is provided with a hose,
nozzle, drain, and in the case of fluorescent penetrant, a black light. Figure 2-16 is a typical wash station with a good
spray shown. The rinsing procedures used for removal of water washable penetrant, Method A, and postemulsifiable
penetrant, Method B (after emulsification) are almost identical. The difference is in controlling the rinse time. Rinse
times for Method A penetrants are very critical as the entrapped water washable penetrant can be removed from
discontinuities if the time is not controlled. Entrapped postemulsifiable penetrants that have not been diffused with
emulsifier resist removal, and rinse times are not as critical. The conditions and procedures described in the following
paragraphs are applicable to both water washable and postemulsifiable penetrants.
Figure 2-16. A Typical Wash or Rinse Station.