Current through Register Vol. 46, No. 12, March 20, 2024
(a) General. Open surface tank operations
creating dangerous air contaminants shall be provided with ventilation to
control such contaminants. (See Industrial Code Part [Rule No.] 18.)
(b) Classes of operations. Open surface tank
operations are classified into groups in accordance with both hazard potential
and rate of contaminant release as set forth in section 18.14 of Industrial
Code Part (Rule No.) 18.
(c)
Humidity control. When heat is added to the workroom to prevent the
condensation of water vapor evaporated from open tanks into mist, such
additional heat shall be so controlled that it does not raise the wet bulb
temperature in the lower six feet of the workroom above 80 degrees
Fahrenheit.
(d) Clean-out doors.
Tanks or machines used for cleaning by solvents and having a surface vapor area
of more than two square feet shall be equipped with suitable clean-out or
sludge doors located near the bottom of each tank or still. Such doors shall be
constructed and maintained so that there is no leakage of solvent when
closed.
(e) Solvent transfer.
(1) Transfer of flammable solvents from
containers shall be by means of a hose or pipe leading to the bottom of the
tank being filled. Containers between which the transfer is being made shall be
electrically bonded and grounded with a resistance of less than 25
ohms.
(2) Volatile solvents shall
not be stored or transferred in uncovered vessels.
(f) Vapor phase degreasing.
(1) Freeboard. The level of the vapors shall
be kept below the top edge of the tank by a distance equal to at least one-half
the tank width or 36 inches, whichever is less.
(2) Heating.
(i) Gas. Where gas is used as fuel for
heating, the combustion chamber shall be of tight construction, except for
necessary combustion and flue openings. Mechanically ventilated flues shall be
independent of the exhaust duct. Natural draft flues shall be provided with
draft diverters. All flues shall be constructed of corrosion-resistant
material.
(ii) Electric. Electric
heating units shall be constructed of materials resistant to the tank contents
and shall be constructed and installed so as to prevent hot spots.
(3) Thermostatic control. Every
tank shall be provided with two thermostats, one of which shall be connected to
control or shut off the source of heat when the contents reach a temperature
not higher than 20 degrees Fahrenheit in excess of the boiling point of the
solvent in its uncontaminated state and the other of which shall be located
above the vapor zone and be adjusted to shut off the source of heat when the
temperature in the zone of the thermostat is at the boiling point of the
solvent.
(4) Condensers. Tanks
shall be equipped with condensing or cooling surfaces consisting of pipes,
coils, water jackets or any combination thereof located on at least two sides
in the upper portion of the tank above the solvent liquid level. Water,
refrigerant or other cooling media shall be circulated through the condenser
whenever the tank is in operation.
(g) Operation.
(1) Where tanks are provided with loading
hoists, the hoists shall be designed to raise and lower the work at a speed not
greater than 11 feet per minute.
(2) All products after immersion in solvents
shall be held in the vapor zone of the tank and shall not be withdrawn from the
tank until the product reaches the vapor temperature as evidenced by the
stopping of vapor condensation on the product.
(3) Loading racks shall be of metal or
equally impervious material.
(4)
The horizontal cross section area of product or rack shall not be greater than
two-thirds of the horizontal cross section area of the tank.
(h) Welding and open flame work.
No work involving welding, open flames or other sources of ignition shall be
done at or about any equipment for open surface tank operations unless such
equipment has first been thoroughly cleaned of all flammable or volatile
solvents and their vapors or is protected by distance or by shielding against
accidental ignition or heating from such work.
(i) Special precautions for cyanide.
(1) Where rinse, acid and cyanide tanks are
so installed and used that any of them may be contaminated with cyanide or
acid, such tanks shall be provided with local exhaust ventilation.
(2) Cyanide tanks shall not be provided with
drains or overflows which will allow the tank contents to mix with liquid
drained from other tanks either on the floor or in floor drains unless the
cyanide drainage has been properly neutralized.
(3) Cyanide salts shall be stored in a locked
enclosure and set above the level of any floor on which acid carboys are
stored.