Section 3290. Control technology guidelines

A. Conveyorized degreasing.

1. Control requirements.

a. The degreaser (if the air/vapor interface is larger than 20 ft²) should be equipped with one of the following vapor control methods:

(1) Refrigerated chiller (a secondary set of condensing coils operating with a coolant of less than 40°F).

(2) Carbon adsorption system, with ventilation of 50 cfm/ft² or greater of conveyor opening area (when down-time covers are open), and exhausting less than 25 ppm of solvent by volume averaged over a complete adsorption cycle.

(3) Any method of equal or greater control efficiency to the methods in subdivisions A 1 a (1) and (2) of this section, provided such method is approved by the board.

b. The degreaser should be equipped with either a drying tunnel, or other means such as rotating (tumbling) basket, sufficient to prevent cleaned parts from carrying out solvent liquid or vapor.

c. The degreaser should be equipped with all of the following control devices:

(1) A device to prevent heat input unless there is adequate coolant.

(2) The spray shall be equipped with a device that will prevent spraying unless the degreaser is operating normally.

(3) A device to shut off the heat if the vapor level rises above a predetermined level.

d. Entrances and exits should silhouette work loads so that the average clearance (between the largest parts and the edge of the degreaser opening) is either four inches or 10% of the width of the opening, whichever is less.

e. Covers should be provided for closing off the entrance and exit during shutdown, heat-up and cool-down.

2. Operating requirements.

a. Exhausting ventilation should not exceed 65 cfm/ft² of degreaser open area, unless necessary to meet the requirements of any regulations promulgated by the U.S. Occupational Safety and Health Administration. Fans shall not be used near the degreaser opening.

b. Carry-out vapor losses should be minimized by racking parts to allow full drainage and maintaining vertical conveyor speed at less than 11 ft/min.

c. Waste solvent should not be disposed of or transferred to another party such that greater than 20% of the waste (by weight) can evaporate into the atmosphere. Waste solvent should only be stored in closed containers.

d. Solvent leaks should be repaired immediately or the degreaser should be shutdown.

e. Water should not be visibly detectable in the solvent exiting the water separator.

f. Down-time cover should be placed over entrances and exits of conveyorized degreaser immediately after the conveyor and exhaust are shutdown and removed just before they are started up.

B. Open top vapor degreasing.

1. Control requirements.

a. Covers should be provided that can be opened and closed easily without disturbing the vapor zone.

b. The degreaser should be equipped with all of the following control devices:

(1) A device to prevent heat input unless there is adequate coolant.

(2) The spray should be equipped with a method that will prevent spraying unless the degreaser is operating normally.

c. Degreaser should be equipped with one of the following vapor control methods:

(1) Freeboard ratio equal to or greater than 0.75. If the open area is larger than 10 ft², the cover should be powered.

(2) Refrigerated chiller (a secondary set of condensing coils operating with a coolant of less than 40°F).

(3) Enclosed design (cover or door opens only when the dry part is actually entering or exiting the degreaser).

(4) Carbon adsorption system, with ventilation of 50 cfm/ft² or greater of air/vapor area (when cover is open), and exhausting less than 25 ppm solvent by volume averaged over one complete adsorption cycle.

(5) Any method of equal or greater control efficiency to the methods in subdivisions B 1 c (1) through (4) of this section, provided such method is approved by the board.

d. A permanent label, summarizing operating procedures in subdivisions B 2 a through f of this section, should be placed in a conspicuous location on or near the degreaser.

2. Operating requirements.

a. The cover should be kept closed at all times except when processing work loads through the degreaser.

b. Carry-out vapor losses should be minimized by:

(1) Racking parts to allow full drainage;

(2) Moving parts in and out of the degreaser at less than 11 ft/min;

(3) Degreasing the work load in the vapor zone at least 30 seconds or until condensation ceases, whichever is longer;

(4) Tipping out any pools of solvent on the cleaned parts before removal; and

(5) Allowing parts to dry within the degreaser for at least 15 seconds or until visually dry, whichever is longer.

c. Porous or absorbent materials, such as cloth, leather, wood or rope should not be degreased.

d. Work loads should not occupy more than half of the degreaser's open top area.

e. The vapor level should not drop more than four inches when the work load enters the vapor zone. However, for certain specific solvent vapor degreasing operations where of necessity very large masses are required to be degreased at one time, such as large castings and fabricated assemblies, the manufacturers design should accommodate a drop of the vapor-air interface of more than four inches. This introduction of such large masses of necessity causes significant vapor-air interface drop and so the problem must be resolved by engineering of the degreaser in these cases rather than by limiting the amount of air-vapor interface drop.

f. Spraying above the vapor level should not be done.

g. Solvent leaks should be repaired immediately or the degreaser shutdown.

h. Waste solvent, still, and sump bottoms shall be collected and stored in closed containers. The closed containers may contain a device that would allow pressure relief, but would not allow liquid solvent to drain from the container.

i. Exhaust ventilation should not exceed 65 cfm/ft² of degreaser open area, unless necessary to meet OSHA requirements. Fans should not be used near the degreaser opening.

j. Water should not be visually detectable in solvent exiting the water separator.

C. Cold cleaning.

1. Control requirements.

a. Covers or enclosed remote reservoirs should be provided. Covers should be designed so that they can be easily operated with one hand. (Covers for larger degreasers may require mechanical assistance, by spring loading, counterweighting or powered systems). Enclosed remote reservoirs should be designed such that they provide reduction effectiveness equivalent to that of a cover.

b. External or internal drainage facilities should be provided to collect and return the solvent to a closed container or a solvent cleaning machine. If a solvent volatility is greater than 0.6 psi measured at 100°F, then the drainage facilities should be internal so that parts are enclosed under the cover while draining. Drainage facilities may be external for applications where an internal type cannot fit into the cleaning system.

c. A permanent label, summarizing the operating procedures in subdivisions C 2 a through c of this section, should be placed in a conspicuous location on or near the degreaser.

d. If used, the solvent spray should be a solid, fluid stream (not a fine, atomized or shower type spray) and at a pressure which does not cause excessive splashing.

e. If a solvent volatility is greater than 0.6 psi measured at 100°F, or if solvent is heated above 120°F, then the degreaser (if the open area is greater than 20 ft²) should be equipped with one of the following vapor control methods:

(1) Freeboard ratio that is equal to or greater than 0.7.

(2) Water cover (solvent should be insoluble in and heavier than water).

(3) Refrigerated chiller (a secondary set of condensing coils operating with a coolant of less than 40°F).

(4) Carbon adsorption system, with ventilation of 50 cfm/ft² or greater of air/vapor area (when down-time covers are open), and exhausting less than 25 ppm of solvent by volume averaged over a complete adsorption cycle.

(5) Any method of equal or greater control efficiency to the methods in subdivisions C 1 e (1) through (4) of this section, provided such method is approved by the board.

2. Operating requirements.

a. Waste solvent should not be disposed of or transferred to another party, such that greater than 20% of the waste (by weight) can evaporate into the atmosphere. Store waste solvent only in closed containers.

b. The degreaser cover should be closed whenever not handling parts in the cleaner.

c. Cleaned parts should drain for at least 15 seconds or until dripping ceases.

D. Disposal of waste solvent from solvent metal cleaning operations should be by one of the following methods:

1. Reclamation (either by outside services or in-house).

2. Incineration.

Historical Notes

Derived from VR120-04-2404, eff. July 1, 1991; amended, Volume 12, Issue 11, eff. April 1, 1996.

Statutory Authority

§ 10.1-1308 of the Code of Virginia.