ANSI/ASHRAE Standard 15-1994, Safety Code For Mechanical Refrigeration

Request from: Sheila S. Oliver, Chief Mechanical Inspector, City of Hollywood, 2600 Hollywood Blvd. 3rd floor, Hollywood, FL 33022

Reference: This request refers to paragraph 8.12.2 & 8.12.3 of ANSI/ASHRAE Standard 15-1994.

Background: A multistory office building has refrigerating mechanical rooms at each end of the building. The offices are served by direct air conditioning systems with refrigerant piping leading from the mechanical rooms to the various floors. The piping passes vertically from the refrigerating machinery rooms to the various floors and then passes horizontally, in a concealed ceiling plenum, in the corridor to each of the office suites.

1. Ms. Oliver’s interpretation of 8.12.2 is that the horizontal run across the corridor is not obstructing passage and is permitted even though this corridor is the means of egress.

2. Ms. Oliver’s interpretation of 8.12.3 is that the part of exception (d) referring to "approved gas-tight, fire resistive duct" applies to both the vertical and the horizontal run of refrigerant piping until the refrigerant piping enters the space being served by the refrigeration system.

Question 1: Is Ms. Oliver’s interpretation of 8.12.2 correct as given in #1 above?

Answer 1: No.

Comment: If installed in a concealed ceiling plenum, the piping is not obstructing passage if the ceiling height satisfies local building code requirements. However, the third sentence of 8.12.2 still applies. Its intent is to both protect the piping from passageway traffic damage, which is met by the refrigerant piping being in a plenum, and to avoid exposing passage users to refrigerant releases during egress if the refrigerant piping fails, which is not met.

Question 2: Is Ms. Oliver’s interpretation of 8.12.3 (d) correct as given in #2 above?

Answer 2: No.

Comment: 8.12.3 is silent on horizontal plenums. 8.12.3 addresses only penetrations of floors, ceilings, or roofs. The requirement for enclosure in "approved gas-tight, fire resistive duct or shaft" as currently written applies only to the vertical penetrations.