Degreasing tanks · Solvent vapour and cold-cleaning tanks versus aqueous dip tanks, freeboard ratio, covers and vapour-level control, overflow and bottom drains, ventilation, heating and filtration
A degreasing tank is an open-top or covered tank in which metal parts are dipped in, sprayed with or exposed to the vapour of a cleaning liquid, either an organic solvent or a heated aqueous or electrolytic cleaner, to remove oils, greases and other soils before finishing. Ask three things first: which cleaning liquid the tank will hold and which rules that brings, what freeboard, cover and vapour or liquid-level controls the design provides, and how the tank is heated, drained, ventilated and kept clean.
Tanks and simple tank-type machines for degreasing metal parts: batch vapour degreasers, immersion and remote-reservoir cold cleaners, and heated aqueous or electrolytic degreasing tanks in a pretreatment line. Complete pretreatment or plating lines, conveyorised in-line washers, ultrasonic cleaners and semiconductor wet benches are outside this page.
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OSHA's dipping and coating rule (29 CFR 1910.123–1910.126) applies when a dip tank holds a liquid other than water and the liquid or its vapour is used to clean, coat or alter the surface of an object; its examples of covered operations include degreasing, pickling, electroplating and cleaning. [2]
US EPA's halogenated solvent cleaning rule (40 CFR Part 63 Subpart T) applies to batch vapour, in-line vapour, in-line cold and batch cold solvent cleaning machines that use methylene chloride, perchloroethylene, trichloroethylene, 1,1,1-trichloroethane, carbon tetrachloride or chloroform above 5 percent by weight; a tank that holds heated but non-boiling solvent is classed as a cold cleaning machine. [1]
Editorial note: a tank for aqueous alkaline or electrolytic cleaning is still a dip tank under OSHA when the liquid is not plain water, but it falls outside the halogenated-solvent rule; give the supplier the chemical and its safety data sheet so heating, materials and ventilation match it.
Give the supplier the cleaning liquid and its safety data sheet, operating temperature, part size, weight and load per basket, throughput, soils to remove, required internal dimensions, heating method and power, filtration or skimming, cover type, drain and overflow arrangement, ventilation connection, electrical supply and the local rules the plant must meet.
02
Subpart T defines freeboard ratio as freeboard height divided by the smaller interior dimension of the machine. An immersion batch cold cleaner must have a tightly fitting cover kept closed except during parts entry and removal plus either a water layer at least 2.5 cm (1.0 in) thick on the solvent or a freeboard ratio of 0.75 or greater; batch vapour and in-line machines must have a freeboard ratio of 0.75 or greater, parts handling no faster than 3.4 m/min (11 ft/min), and each vapour machine needs a sump-heat shut-off if the solvent level drops to the heater coils. [1]
For batch vapour machines with a solvent/air interface of 1.21 m² (13 ft²) or less, Subpart T Table 1 lists ten control combinations, five of which include a freeboard ratio of 1.0, paired with a working-mode cover, superheated vapour, reduced room draft or dwell; the alternative is an idling emission limit of 0.22 kg/h per m² of interface area. [1]
OSHA requires the condenser or vapour-level thermostat of a vapour degreasing tank to keep the vapour level at least 36 in (91 cm) or one-half the tank width, whichever is less, below the top of the tank, and gas-fired heating to keep solvent vapour out of the air-fuel mixture. [5]
Editorial calculation: for a tank with interior 600 mm × 900 mm, the smaller dimension is 600 mm, so a freeboard ratio of 0.75 needs at least 450 mm of freeboard and 1.0 needs 600 mm; half the 600 mm width is 300 mm, which is less than 91 cm, so it sets the OSHA vapour-level depth if 600 mm is the tank width. Ask the supplier to show the freeboard height measured as each rule defines it. [1] [5]
03
For dip tanks using flammable liquids or liquids with flashpoints above 93 °C (199.4 °F), OSHA requires noncombustible construction, trapped overflow piping of at least 3 in diameter for tanks over 150 gal (568 L) or with more than 10 ft² (0.95 m²) of liquid surface, with the overflow connection at least 6 in below the top, and a bottom drain able to empty the tank within five minutes for tanks over 500 gal (1,893 L) unless an automatic closing cover is fitted. [4]
Any dip tank must be strong enough for the expected load, and ventilation must keep airborne concentrations below 25 percent of the lower flammable limit; a cover or floating material may replace or supplement ventilation, and spray degreasing over an open tank must be enclosed and ventilated where feasible. [3] [5]
Editorial note: aqueous degreasing tanks still need lids or extraction for steam and mist, oil skimming or filtration to extend bath life, and a drain valve sized for the bath volume; ask the supplier what is fitted as standard.
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No manufacturer record has been reviewed for this product yet. Send your specification and CNFX will match it against manufacturer records.
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This is a functional reference built from the sources cited; it is not one maker's design.
| Part | Role | Fix in the order |
|---|---|---|
| Tank body | Holds the liquid and load. [3] [4] | Material, wall, internal size. |
| Freeboard and cover | Limits vapour loss. [1] | Freeboard height, cover type. |
| Heater and controls | Heats the bath or sump. [1] [5] | Power, thermostat, low-level cut-out. |
| Condenser coils | Set the vapour level in vapour tanks. [5] | Coil height, chiller. |
| Overflow and drain | Remove liquid safely. [4] | Pipe size, drain time. |
| Ventilation connection | Controls vapour exposure. [3] | Hood or lip exhaust, airflow. |
| Filtration or skimming | Removes soils from the bath. | Filter type, skimmer. |
06
A degreasing tank quotation needs values for your parts and chemistry. The table explains each field, gives published values where a reviewed source states them, and says what to obtain from the supplier.
| Field | What it means and published values | Ask the supplier for |
|---|---|---|
| Tank Capacity (L) | Overflow piping rules start above 568 L for flammable liquids; bottom drain above 1,893 L. [4] | Working and total volume. |
| Working Temperature (°C) | Heated non-boiling solvent counts as cold cleaning. [1] | Range and control band. |
| Heating Power (kW) | Heat-up and holding load. | Power and heat-up time. |
| Tank Material | Noncombustible for flammable liquids. [4] | Grade compatible with the chemical. |
| Insulation Thickness (mm) | Heat loss. | Thickness and cladding. |
| Temperature Control Accuracy (°C) | Bath stability. | Controller and sensor. |
| Electrical Supply (V AC) | Plant supply; hazardous-area wiring in vapour areas. [4] | Voltage and area classification. |
| Degree of Protection | Enclosure rating. | IP rating of panels. |
| Overall Dimensions (L×W×H) (mm) | Freeboard ratio uses the smaller interior dimension. [1] | Interior and overall drawing. |
| Empty Weight (kg) | Floor loading. | Empty and filled weight. |
| Max. Operating Pressure (MPa) | Open tanks run at atmospheric pressure. | Pump and spray pressure if fitted. |
| Agitation Speed (rpm) | Mixer or pump agitation. | Agitation method. |
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Paste it into your enquiry below or into an email to a maker, then replace every bracket.
Chemistry: [solvent or aqueous cleaner; SDS; temperature] Parts: [size; weight; basket load; throughput] Tank: [interior size; freeboard; cover; material] Controls: [heater; thermostat; low-level cut-out; condenser] Safety: [overflow; bottom drain; ventilation; rules to meet] Supply: [drawings; quantity]
No manufacturer record has been reviewed for this product yet. Send your specification and CNFX will match it against manufacturer records.
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Under US EPA Subpart T, batch vapour and in-line halogenated-solvent machines need at least 0.75, and five of the ten Table 1 control options for small machines use 1.0; cold cleaners can use a 0.75 ratio or a water layer with a cover. [1]
OSHA requires at least 36 in (91 cm) or half the tank width, whichever is less. [5]
Yes when it holds a liquid other than water used to clean an object; OSHA lists degreasing among covered operations. [2]
Sources checked 2026-10-11. The US EPA and OSHA texts are regulations for US workplaces; other jurisdictions have their own rules. Design values for your tank must come from the supplier's drawings and the rules that apply at your site.
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