Polymer quenching tank: a PAG quenchant system with concentration, temperature and load-ratio control
Quenching tanks run with water-based polyalkylene glycol (PAG) quenchant · concentration by refractometer, bath held well below the 74 °C separation point, load-to-volume ratio, heat exchanger and contamination control
A polymer quenching tank is a quench tank filled with a water solution of a polyalkylene glycol (PAG) quenchant instead of oil. When hot steel or aluminium enters the bath, the polymer comes out of solution as a film on the part and slows the cooling; the film thickness, and so the quench speed, is set by the concentration, the bath temperature and the agitation. Running one well means measuring concentration on a fixed schedule, keeping the bath far enough below the polymer's separation temperature, sizing the tank volume to the load, and keeping oil and grease out.
Quench tanks and systems operated with aqueous polyalkylene glycol quenchants for steel hardening and aluminium solution treatment: concentration control, bath temperature and heat exchange, load-to-volume ratio, tank coating and contamination. Quench tanks for oil, polymer or water as a class, with agitation sizing and OSHA rules for oil hardening tanks, are covered on the Quench tank page.
CNFX editorial research · Sources checked October 12, 2026 · 3 sources
Set the quench speed with PAG concentration and check it with a refractometer
Dow describes its UCON Quenchant E as an aqueous solution of a liquid organic polymer with a corrosion inhibitor; on hot metal the polymer forms a film whose thickness is governed by the concentration, while bath temperature and agitation also adjust the cooling rate. [2] Quaker Houghton states the same for AQUA-QUENCH 251: as concentration rises, thicker films form, quenching slows and the maximum cooling rate falls. [3]
The table is from GEO Specialty Chemicals' data sheet, measured at 20 °C with a 12.5 mm Inconel 600 probe and moderate agitation. [1] GEO measures concentration by refractive index, with a direct-reading refractometer or a chart converting Brix or refractive index to concentration, and gives kinematic viscosity as a cross-check. [1] Quaker Houghton lists refractometer factors of 2 for AQUA-QUENCH 145 and 2.6 for AQUA-QUENCH 251, the latter conforming to AMS 3025 as a Type 2 quenchant for aluminium alloys such as 2024, 6061 and 7075. [3]
Editorial calculation, taking the factor as the multiplier from refractometer reading to concentration: a 20% AQUA-QUENCH 251 bath reads about 7.7 (20 / 2.6), and a 20% AQUA-QUENCH 145 bath about 10 (20 / 2). GEO's worked top-up example, for a 5,000 L system with a 20% target, adds 250 L of concentrate. [1]
GEOlube Quenchant A concentration
Quench behaviour stated by GEO
3–5%
Better wetting than water; equivalent to a well-agitated water or even brine quench
Around 15%
Cooling rates similar to, or slightly above, fast mineral quench oils; for low-hardenability materials
30–35%
Cooling rates of medium/slow quench oils; for direct-hardening and case-hardening steels
40% and above
Used in aluminium heat treatment in place of hot water quenches
State the quenchant product, the target concentration and its tolerance, the refractometer factor or chart used, and how often concentration is checked.
02
Hold the bath between ambient and 50 °C, well below the 74 °C separation point
All three quenchants in this review separate from water above 74 °C (inverse solubility) and redissolve on cooling: GEO gives a cloud point and separation temperature of 74 °C, Dow 74 °C (165 °F) for UCON Quenchant E, and Quaker Houghton 74 °C for AQUA-QUENCH 251. [1][2][3]
GEO limits bath operating temperature to between ambient and 50 °C, because higher temperatures can cause the whole tank to invert, and asks for close control of the chosen temperature since it also changes the cooling behaviour. It recommends fitting the system with a heat exchanger and notes that the temperature rise is about half that seen in oil. [1]
To limit the risk of bulk tank inversion, GEO recommends a load-to-quench-volume ratio of 1:12.5 (kg to litres), with 1:10 as the minimum acceptable. [1] Editorial calculation: a 400 kg load calls for 5,000 L of quenchant at 1:12.5, and at least 4,000 L at 1:10.
GEO states that agitation must always be built into a polymer quench system to prevent local overheating and starvation, and that a two-pack epoxy or polyurethane paint system is satisfactory for tank surfaces up to 65 °C. [1] Dow notes that its quenchant freezes below 0 °C and must be thawed and mixed before use, and that the main make-up is water lost by evaporation. [2]
Specify the heat exchanger duty for the heaviest load per hour, the bath temperature setpoint and band, and the tank volume against the maximum load weight.
03
Keep oil, grease and washer chemicals out of the polymer bath
GEO measured how 1% of various contaminants changes the GM Quenchometer time of an 11.2% GEOlube Quenchant A solution, where a longer time means a slower quench. [1]
Editorial calculation from the table: 1% of soluble oil more than doubles the quenchometer time (18.7 / 8.1 ≈ 2.3), while 1% of washing compound shortens it by about a third. [1]
GEO also advises keeping circulating pump inlets covered by fluid at all times, because air drawn in through pumps aggravates foaming, and cleaning oil residues from the equipment before the first fill. [1] Dow warns that steam and small amounts of organic vapours are released during quenching and asks for adequate ventilation round quench tanks. [2]
Contaminant (1%)
Quenchometer time (s)
None
8.1
Synthetic cutting fluid
8.5
General-purpose cutting oil
12.6
Petroleum oil
17.9
Soluble oil
18.7
General-purpose grease
20.1
Inorganic washing machine compound
5.2
04
Data for a polymer quenching tank enquiry
Paste it into your enquiry below or into an email to a maker, then replace every bracket.
Parts: [material; section size; maximum load weight per quench]
Quenchant: [PAG product; target concentration]
Tank: [working volume; load-to-volume ratio; coating]
Temperature: [setpoint; tolerance; heat exchanger duty]
Agitation: [pumps or propellers; flow through the load]
Control: [refractometer or viscosity checks; top-up system]
Contamination: [oil skimming; filtration; rinse before quench]
Extraction: [ventilation over the tank]
1 company lists this product among what they make. Company figures are quoted from each
company's own website; every card states where the relationship came from.
LuJiang ChengChi Industrial Furnace Factory
Manufacturing site to be confirmed for the order
Lists quench tanks (淬火槽) built with a tank, piping, overflow trough, heater, cooler, agitator, fire extinguishing and fume extraction, alongside heat-treatment furnaces; the quenchant is not specified on the page.
Product scope checked 2026-10-12
Quench tanks listed · profile compiled by CNFX from public sources
Explore company information and manufacturing capabilities, then discuss the scope of your project with a relevant supplier.
Share this page
Compiled and source-reviewed by the CNFX editorial team.
Each manufacturer above links to the page on that company's own website where the product is listed, with the date we checked it. How we source and review
· Page last updated 13 October 2026
Buyer questions
What concentration should a polymer quench bath run at?
It depends on the cooling rate needed: GEO gives 3–5% for water-like quenching, around 15% for fast-oil-like rates and 30–35% for medium or slow oil rates, with 40% and above used for aluminium. [1]
Why must a polymer quench bath stay below 50 °C?
The PAG separates from water above about 74 °C; GEO limits the bath to ambient–50 °C to avoid bulk tank inversion. [1][2][3]
How big should a polymer quench tank be for the load?
GEO recommends 12.5 litres of quenchant per kilogram of load, with 10 litres per kilogram as the minimum. [1]
Sources and what still needs a direct check
Sources checked 2026-10-12. Concentration, temperature, load ratio and contamination data come from GEO Specialty Chemicals' GEOlube Quenchant A data sheet; separation temperature and film behaviour from Dow's UCON Quenchant E and E-NN data sheet; refractometer factors and AMS 3025 conformity from Quaker Houghton's quenching product sheets.
