Teledyne 6712FR Refrigerated Sampler Appendix C General Safety Procedures, C.1.2, Planning

6712FR Refrigerated Sampler

Appendix C General Safety Procedures

		Sharp Edges – Sharp edges of items in or near a manhole may
		cause cuts or bruises.
		Lifting Injuries – Unless proper tools are used to remove
		manhole covers, back injuries or injuries to hands or feet may
		result.
C.1.2	Planning	Advance planning should include arrangements for test
		equipment, tools, ventilating equipment, protective clothing,
		traffic warning devices, ladders, safety harness, and adequate
		number of personnel. Hasty actions may result in serious
		injuries. Time spent in the manhole should be kept to a
		minimum.
C.1.3	Adverse Atmospheres	[Refer to Table C-1,Hazardous Gases, at the end of this
		appendix.] Before workers enter a manhole, tests should be made
		for explosive atmosphere, presence of hydrogen sulfide, and
		oxygen deficiency. Combustible or toxic vapors may be heavier
		than air, so the tests on the atmosphere must be run at least 3/4 of
		the way down the manhole.
		Whenever adverse atmosphere is encountered, forced ventilation
		must be used to create safe conditions. After the ventilating
		equipment has been operated for a few minutes, the atmosphere
		in the manhole should be retested before anyone enters the
		manhole.
		When explosive conditions are encountered, the ventilating
		blower should be placed upwind to prevent igniting any gas that
		is emerging from the opening. When a gasoline engine blower is
		used, it must be located so that exhaust fumes cannot enter the
		manhole.
		If testing equipment is not available, the manhole should be
		assumed to contain an unsafe atmosphere and forced ventilation
		must be provided. It should never be assumed that a manhole is
		safe just because there is no odor or the manhole has been
		entered previously.
C.1.4	Entering Manholes	Since the top of the manhole is usually flush with the sur-
		rounding surface, there may not be anything for the person who
		is entering the manhole to grab on to steady himself. Persons
		who are entering manholes should not be permitted to carry any-
		thing in their hands as they enter the manhole, to ensure that
		their hands will be free to hold on or grab if they slip. A good
		method for entering a manhole is to sit on the surface facing the
		manhole steps or ladder, with the feet in the hole and the arms
		straddling the opening for support. As the body slides forward
		and downward, the feet can engage a rung, and the back can rest
		against the opposite side of the opening. If there is any doubt

about the soundness of the manhole steps, a portable ladder should be used.

A person should never enter a manhole unless he is wearing per- sonal safety equipment, including a safety harness and a hard hat. Two persons should be stationed at the surface continuously while anyone is working inside a manhole, to lift him out if he is

C-2