D-1
4220 Flow Meter
Appendix D General Safety Procedures
In field installations of 4220 Flow Meters and associated
equipment, the safety of the personnel involved should be the
foremost consideration. The following sections provide safety pro-
cedures for working in and around manholes and sewers. the
first section offers general safety advice. The second section deals
with the special problem of hazardous gases found in sewers.
WARNING
The 4220 Flow Meter has not been approved for use in
hazardous locations as defined by the National Electrical
Code.
CAUTION
Before any flow meter is installed, the proper safety precau-
tions must be taken. The following discussions of safety proce-
dures are only general guidelines. Each situation in which you
install a flow meter varies. You must take into account the indi-
vidual circumstances you are in. Additional safety consider-
ations, other than those discussed here, may be required.

D.1 Practical Safety

Precautions

The following procedures are those used by Black & Veatch, a
respected consulting firm, and are published here by permission.
“Field personnel must keep safety uppermost in their minds at
all times. When working above ground, rules of common sense
and safety prevail. However, when entering manholes, strict
safety procedures must be observed. Failure to do so could jeop-
ardize not only your own life, but also the lives of other crew
members.
“1. Hazards. There are many hazards connected with entering
manholes. Some of the most common hazards are:
Adverse Atmosphere. The manhole may contain flammable or
poisonous gases or the atmosphere may be deficient in oxygen.
Forced ventilation may be necessary.
Deteriorated Rungs. Manhole steps may be corroded and not
strong enough to support a man. It may be difficult to inspect the
rungs because of poor lighting.
Traffic. Whenever manholes are located in the traveled way,
barricades and warning devices are essential to direct traffic
away from an open manhole.
Falling Object. Items placed near the manhole opening may
fall and injure a worker in the manhole.
Sharp Edges. Sharp edges of items in or near a manhole may
cause cuts or bruises.