CHLORINE HANDLING MANUAL
IM 25.000AA UA (B/6-00) PAGE 9
Tank cars are unloaded by means of one of the liquid valves.
One of the gas valves can be connected to the system to
permit pressure testing with gaseous chlorine rather than
liquid. The flexible connection used for tank car unloading
must be designed for and installed in such a manner to allow
for the significant increase in height as the car unloads. Since
tank car pressure is the only force causing the chlorine to
discharge, many cars are padded with dry air by the producer
or the user. Reference to Chlorine Institute Pamphlet 66,
Chlorine Tank Car Loading, Unloading, Air Padding, Hy-
drostatic Testing, should be made for information on user air
padding. It is essential that air padding pressure be kept as
low as possible for satisfactory operation of the chlorination
equipment since excessive air padding pressures can have a
negative impact on evaporator performance. The depletion
of the liquid chlorine supply in the car is accompanied by a
sharp drop in tank car pressure.
After the angle valve is closed and the discharge line emp-
tied, the piping may be disconnected. The valve outlet plugs
should be replaced and the discharge piping capped imme-
diately.
4 PIPING
4.1 PIPING MATERIALS AND JOINTS
If the chlorinator capacity is low enough, the vacuum regu-
lator or the complete chlorinator may be mounted directly on
a cylinder or ton container valve, totally eliminating pres-
sure piping. In this case, reference to the equipment instruc-
tion book provides all necessary details.
Pressure connections from all chlorine containers are nor-
mally made by means of flexible connections made of copper
tubing. Use yoke type connections at container valves. The
chlorinator or vacuum regulator instruction book should be
referred to for details for use of flexible connections along
with the required auxiliary cylinder or ton container valves,
header valves, and auxiliary header valves (if required).
WARNING: ALWAYS REPLACE FLEXIBLE CON-
NECTIONS ANNUALLY (OR SOONER IF THERE IS
EVIDENCE OF DETERIORATION).
The usual practice for chlorine liquid or gas pressure lines,
at the commonly encountered pressures and temperatures at
chlorinator installations, is the use of 3/4 or 1.0 inch sched-
ule 80 carbon steel seamless pipe with Class 3000 forged
steel fittings; two-bolt flanges (commonly referred to as oval
ammonia unions) are also often used. Both screwed and
socket welded construction are common. Threaded joints
should be made up using litharge and glycerine for perma-
nent joints, white lead or TFE tape for others.
To facilitate maintenance, the number of line valves should
be kept to a minimum. Insulation is required only in those
cases where it is necessary to prevent chlorine gas lines from
becoming chilled, or liquid lines from becoming overheated.
More complete details, along with ASTM and ANSI speci-
fications, can be obtained by referring to Chlorine Institute
Pamphlet 6, Piping Systems For Dry Chlorine.
WARNING: TWO COMMON CAUSES OF CHLO-
RINE PIPING LEAKS ARE:
1. RE-USE OF GASKETS. THIS SHOULD NEVER BE
DONE. ALWAYS HAVE AN ADEQUATE SUPPLY ON
HAND AND ALWAYS USE NEW GASKETS OF THE
CORRECT MATERIAL AND SIZE AS IDENTIFIED
ON THE EQUIPMENT PARTS DRAWING.
2. IMPROPERLY MADE-UP THREADED PIPE
JOINTS. SEE CHLORINE INSTITUTE MANUAL OR
PAMPHLET 6 FOR RECOMMENDED PROCEDURE.
4.2 GAS PIPING INSTALLATION REQUIREMENTS
Reliquefaction of a gas should be avoided. If liquid chlorine
is carried downstream to the chlorinator or vacuum piping,
it may soften the plastic components and affect their struc-
tural strength. Liquid can wash any collected contaminants
into the vacuum regulator and can also cause erratic surging,
freezing, and pressure release, which can damage the dia-
phragm and control valves. Cold conditions in a gas pipe line
(cold to the touch, dripping of water condensed from the
atmosphere, frost, ice) are an indication that liquid chlorine
is present in the line and is flashing to gas. Refer to the proper
guidelines that follow.
It is important to observe the correct temperature conditions
in conducting chlorine gas under pressure from the location
of the containers to the point of use. To avoid difficulty with
reliquefaction of chlorine, pressure piping and control equip-
ment receiving gas under pressure should be at a higher
temperature than that of the chlorine containers. In general,
a difference of 5° to 10° F is recommended.
Pitch pressure lines uphill from the gas source toward the
chlorinators if possible.
Install a pressure reducing valve or the chlorinator vacuum
regulator close to, but higher than, the source of gas. The use
of a chlorine pressure reducing valve is also recommended
in those localities where severe temperature changes are likely
to be encountered during a 24-hour period.
It is preferable to run chlorine pressure gas lines overhead
through relatively warm areas rather than along the floor or
through basement areas where lower temperatures may be
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