OaklandMechEng
Mechanical
- Jan 5, 2009
- 5
Greetings Forum,
I have a situation where we want to look at a marine transfer operation that transfers marine gas oil (flash point=131F, NEC & API Class II liquid).
The guidelines provided for this situation (figure 19) in API 500 (and in NEC article 500) apply to flammable (Flash Point < 100F, Class I liquids), but there are no guidelines that I could find for class II combustible products (flash point > 100F, but <140 F).
All I could find that might apply are the general guidelines in Section 5.2.3 for Class II Liquids: "The chance of ignition of vapors of Class II liquids is not as great as ignition of the vapors of Class I liquids. Their vapors normally do not travel as far as the vapors of Class I liquids. Normally, except near the points of release, Class II liquids do not produce vapors of sufficient quantity to be considered for electrical classification purposes".
I take this to mean that the classified area will be less than what is shown in Figure 19, as that applies to more volatile, flammable products, but how much less?
Class II liquids seem to be in a sort of grey area, as Class I situations are all very well covered in API 500, and you don't typically classify Class III liquids, but Class II liquids fall somewhere in the middle.
How do people generally handle the hazardous classification of Class II liquids?
Many Thanks!
OaklandMechEng
I have a situation where we want to look at a marine transfer operation that transfers marine gas oil (flash point=131F, NEC & API Class II liquid).
The guidelines provided for this situation (figure 19) in API 500 (and in NEC article 500) apply to flammable (Flash Point < 100F, Class I liquids), but there are no guidelines that I could find for class II combustible products (flash point > 100F, but <140 F).
All I could find that might apply are the general guidelines in Section 5.2.3 for Class II Liquids: "The chance of ignition of vapors of Class II liquids is not as great as ignition of the vapors of Class I liquids. Their vapors normally do not travel as far as the vapors of Class I liquids. Normally, except near the points of release, Class II liquids do not produce vapors of sufficient quantity to be considered for electrical classification purposes".
I take this to mean that the classified area will be less than what is shown in Figure 19, as that applies to more volatile, flammable products, but how much less?
Class II liquids seem to be in a sort of grey area, as Class I situations are all very well covered in API 500, and you don't typically classify Class III liquids, but Class II liquids fall somewhere in the middle.
How do people generally handle the hazardous classification of Class II liquids?
Many Thanks!
OaklandMechEng
