SECTION 5.13  DIP TANKS

Subsection 5.13.1.  Location

Room design

5.13.1.1.  (1)  If a dip tank operation involves flammable liquids or combustible liquids and the quantity of liquids exceeds 45 L or the liquid surface area exceeds 0.42 m², the operation shall be

(a)   conducted in a room designed for that purpose, and
(b)   separated from the remainder of the building by a fire separation having a fire-resistance rating not less than 2 h.

Prohibition for basements

5.13.1.2.  Dip tanks shall not be located in basements.

Subsection 5.13.2.  Construction

Floors

5.13.2.1.  The floor of any room where dip tanks are located shall be made liquid-tight with material that is impervious to the liquid in the tank, have permanent curbs and be drained to a place of safe discharge.

Materials

5.13.2.2.  (1)  Dip tanks and drain boards shall be constructed of noncombustible material with steel, reinforced concrete or masonry supports.

(2)  Drain boards shall be arranged to drain back to the dip tank.

Height above floor

5.13.2.3.  The top of a dip tank shall not be less than 150 mm above the floor of the room in which it is located.

Cover construction

5.13.2.4.  Dip tank covers as required in Articles 5.13.6.2. and 5.13.6.3. shall be of noncombustible materials.

Cover design

5.13.2.5.  Dip tank covers shall overlap the sides of the tank by 25 mm and shall have a recess or flange extending down around the tank.

Cover maintenance

5.13.2.6.  Dip tank covers shall be maintained in good operating condition.

Subsection 5.13.3.  Overflow and Drain Pipes

Liquid levels

5.13.3.1.  The liquid level in a dip tank shall be kept not less than 150 mm below the top of the tank.

Overflow pipes

5.13.3.2.  Dip tanks having a capacity in excess of 550 L or having a liquid surface area in excess of 1 m² shall be equipped with a properly trapped overflow pipe that leads to a safe location outside the building or to a closed, vented salvage tank conforming to Subsection 5.13.4.

Location of overflow

5.13.3.3.  The centre line of the overflow connection to a dip tank shall be 150 mm below the top of the tank.

Overflow size

5.13.3.4.  Overflow pipe sizes for dip tanks shall conform to Table 5.13.3.A.

TABLE 5.13.3.A.

Forming Part of Article 5.13.3.4.

Overflow connection

5.13.3.5.  Overflow pipes shall be connected to dip tanks by a flared outlet.

Piping connections

5.13.3.6.  Piping connections for drains and overflow lines shall be designed so as to allow for easy access to their interiors for cleaning purposes.

Bottom drains

5.13.3.7.  Dip tanks of over 2300 L liquid capacity shall be equipped with bottom drains capable of being operated both automatically and manually to drain the tank quickly in the event of fire.

Salvage tank

5.13.3.8.  Bottom drains from dip tanks shall be trapped and shall discharge to a closed, vented salvage tank.

Drain size

5.13.3.9.  Bottom drain sizes for dip tanks shall conform to Table 5.13.3.B.

TABLE 5.13.3.B.

Forming Part of Article 5.13.3.9.

Manual operation of bottom drains

5.13.3.10.  Manual operation of bottom drains shall be from an accessible location not affected by a fire in or around the dip tank.

Automatic pumps

5.13.3.11.  Where gravity flow is not practical, automatic pumps shall be installed on drain lines from dip tanks.

Pump for salvage tank

5.13.3.12.  Where salvage tanks are used, pumping arrangements shall be provided for the transfer of their contents for disposal.

Subsection 5.13.4.  Salvage Tanks

Use

5.13.4.1.  Salvage tanks shall be used only for temporary storage purposes.

Capacity

5.13.4.2.  The capacity of a salvage tank shall be 20% greater than the capacity of the dip tank or tanks to which it is connected.

Location

5.13.4.3.  Salvage tanks shall be located underground outside the building, or inside a building in an enclosure separated from the remainder of the building by a fire separation having a fire-resistance rating of not less than 2 h.

Vent pipes

5.13.4.4.  Salvage tanks shall be provided with vent pipes that meet the requirements of Subsection 4.3.5. for aboveground storage tanks or Subsection 4.3.10. for underground storage tanks.

Subsection 5.13.5.  Control of Fire Hazards

Ventilation

5.13.5.1.  Ventilation shall be provided to confine all flammable vapour concentrations exceeding 25% of the lower explosive limit to within 600 mm of the dip tank, drain board and freshly coated work.

Interlock for dipping conveyor

5.13.5.2.  Ventilating systems shall be arranged so that the failure of any ventilation fan as sensed by air flow will automatically stop the dipping conveyor systems and sound an alarm.

Interlock for heating

5.13.5.3.  The heating system used in drying operations shall be interlocked so that it cannot be started until the associated ventilation system is in operation.

Conveyor systems

5.13.5.4.  Conveyor systems utilized in conjunction with dip tanks shall be designed to stop automatically with the actuation of an automatic fixed extinguishing system or a manual fire alarm.

Purging interlocks

5.13.5.5.  Where there is a possible source of ignition in a drying operation, interlocks shall be installed to provide for purging before the heating system can be started and for automatic shutdown if the ventilation system should fail.

Electrical installations

5.13.5.6.  Where flammable liquids and combustible liquids contained in dip tanks are heated or have a flash point below 43°C, the electrical installation shall conform to the Electrical Safety Code made under the Electricity Act, 1998.

Flammable and combustible liquids

5.13.5.7.  (1)  The storage and handling of flammable liquids and combustible liquids shall be in conformance with Part 4.

(2)  The total number of containers for flammable liquids and combustible liquids in a dip tank area shall not exceed that required for one day’s operations.

Smoking and ignition sources prohibited

5.13.5.8.  Smoking shall not take place and open flames, spark-producing devices and heated surfaces having a temperature sufficient to ignite vapours shall not be used in the vapour area of a dip tank.

Signs prohibiting smoking

5.13.5.9.  Signs that prohibit smoking and that conform to Article 2.4.3.2. shall be posted conspicuously in the vicinity of dip tanks.

Subsection 5.13.6.  Fire Protection

Automatic sprinklers

5.13.6.1.  Dip tanks shall be located only in rooms protected by an automatic sprinkler system installed in conformance with NFPA 13, “Standard for the Installation of Sprinkler Systems”.

Tank covers and extinguishing systems

5.13.6.2.  (1)  Dip tanks with over 550 L capacity or with over 1 m² liquid surface area shall be protected by

(a)   a cover actuated by a device that

(i)   automatically closes the cover in the event of a fire, and
(ii)   permits manual operation of the cover, or

(b)   an approved automatic extinguishing system of a water spray, foam, carbon dioxide or dry chemical type.

Flammable liquids or combustible liquids

5.13.6.3.  Dip tanks containing either a flammable liquid or combustible liquid with a flash point less than 43°C or a heated combustible liquid giving off flammable vapours shall conform to Article 5.13.6.2. when the capacity exceeds 45 L or when the liquid surface area exceeds 0.4 m².

Portable extinguishers

5.13.6.4.  Areas in the vicinity of dip tanks shall be provided with portable extinguishers in conformance with Section 6.2.