Section 40. Atmospheric testing

A. Where mechanical ventilation is utilized in accordance with subsection C, the qualified person shall assure that each confined space into which an employee may be required to enter is tested immediately prior to entry using direct reading instruments or go/no-go instruments with preset values, with remote sampling capacity for the following conditions:

1. Potential flammable hazard; and

2. Toxic materials known or expected to be present.

In the absence of mechanical ventilation as specified in subsection C, the qualified person shall also test for oxygen levels prior to entry. The testing of the atmosphere for a particular toxic material is not necessary where the presence of that material is known by virtue of a previous test and appropriate personal protective equipment to protect against that material is utilized.

B. When an attendant has been assigned, as prescribed by 16VAC25-70-50 A, a qualified person shall perform atmospheric testing during occupancy at intervals dependent on the possibility of changing conditions, but in no case less frequently than hourly. Atmospheric test results must be recorded on the permit at least hourly in accordance with 16VAC25-70-60 B.

C. When a non-attendant entry is permitted, as allowed by 16VAC25-70-50 A, at least one entrant shall use a continuous monitoring device equipped with an alarm and capable of evaluating oxygen concentrations and combustible gas concentrations in the confined space. When large confined spaces are entered, a sufficient number of monitoring devices shall be either worn or located in the work area to adequately monitor the atmosphere. Where continuous mechanical ventilation which conforms to the Bell System Practices for Testing and Ventilating Manholes [§ 620-140-501 (4.01-7.05) (1976)] is utilized, monitoring for oxygen concentrations in the confined space shall not be required.

D. Each atmospheric testing instrument shall be calibrated according to the manufacturer's instructions or, if no manufacturer's specifications exist, at least yearly, and field checked immediately prior to its use. Instruments which are out of calibration or fail a field check cannot be used until they are properly calibrated.

Historical Notes

Derived from VR425-02-30, § 4, eff. November 15, 1987; amended, eff. July 1, 1988.

Statutory Authority

§ 40.1-22(5) of the Code of Virginia.