1-805-484-2992
Quotes - Engineering - SalesA representative sample, at a temperature a technician can hold
Cool one liter without touching the loop
Every WFI loop is sampled at the return, the tank and a set of use points on a schedule, and every pure steam generator is sampled as condensate. The sample has to be the loop: same water, same bioburden, same endotoxin, at a temperature that fits in a bottle without flashing or scalding the technician. A sample cooler is a very small double tubesheet exchanger, 1 to 5 sq ft, that takes 0.5 to 2 gpm through a sanitary sample valve and drops it from 80 C to 20 C.
The engineering is not the heat transfer. It is making sure the cooler adds nothing, holds nothing between samples and can be proven clean.
Design for a sample that means something
What a QC group needs the cooler to be
A sample cooler is on the sampling SOP, so it is validated equipment. It can defeat a sample three ways: by holding stagnant water between samples that grows organisms, by a rolled tube joint that lets tower water into the sample, or by an internal surface that sheds particles or rouge. The design answer is a double tubesheet unit with the sample in a single pass of electropolished 316L tube, tower or chilled water on the shell across an open gap, vertical so the tube drains through the outlet valve, and no elastomer in the sample path but the clamp gasket at the loop valve. Small units are often a coil rather than a bundle; the coil is still double tubesheet at both ends.
The flush, and why the outlet valve matters
The first water out of a sample cooler is whatever sat in it since the last sample, and it is never the loop. The SOP flushes the cooler for a set time before the bottle opens; at 1 gpm through a cooler holding 0.3 liters, thirty seconds clears it ten times over, and most SOPs call for a minute or more with the loop-side valve fully open. The outlet is a sanitary valve, not a hose barb, because a hose is a dead leg with a bacterial population of its own and cannot be steamed. Between samples the loop-side valve is closed, the outlet stays open, and the cooler drains dry by gravity. A cooler that holds water between samples is the one the environmental monitoring trend catches first.
Pure steam sample coolers
Pure steam is sampled as condensate, and the condensate is tested against the WFI monograph. The sample cooler on a pure steam header takes steam at 30 to 45 psig, condenses it and sub-cools the condensate to 20 to 30 C in one small unit. It sees 135 C on every sample, which sterilizes it, and the concern shifts from bioburden to non-condensable gases and superheat: the cooler is vented so air in the header does not blanket the tube, and the sample valve is a sanitary steam-rated valve with a slow opening so the first slug of steam does not hammer the coil. The shell is rated for the header pressure in case the tube fails; a domestic sample cooler with a 75 psig shell is not the right part.
The common mistake
Buying a boiler-house sample cooler. The coil-in-a-can units sold for power plant water are single tubesheet, 304 or carbon steel shell, rolled joints and a mill-finish coil, at a tenth of the price. On a WFI loop the rolled joint weeps tower water into the sample, the mill finish grows a film, the unit cannot be steamed, and QC spends a quarter chasing a bioburden trend that lives in the cooler. HeatX builds the sanitary version with the same five-minute installation and the right metallurgy.
Send the loop or header conditions, the number of sample points and the cooling water, and the coolers ship as a set. Call and talk it through with an engineer: 1-805-484-2992
Sample cooler process conditions
A sample cooler runs briefly and must leave nothing behind. The rows below show what it is built to handle at a loop or steam sampling point; send your sample source and valve arrangement with the quote request.
| Condition | Detail |
| Product | WFI or PW from a loop; pure steam condensate at a generator or header sample point |
| Flow range | 0.5 to 2 gpm during the sample; zero between samples |
| Temperatures in / out | 80 C to 20 to 25 C for loop water; 121 to 135 C steam to 20 to 30 C condensate |
| Hold | None; the flush before the sample clears the cooler volume three times |
| Utility | Chilled water 7 C or tower water 30 C on the shell, 2 to 5 gpm |
| Approach | 5 to 10 C; not critical, the outlet is a comfort temperature |
| Construction | Double tubesheet coil or straight-tube 316L, vertical, drains through the sample valve |
| Finish / class | 316L, 15 to 20 Ra electropolished, ASME BPE; steam version rated 150 psig shell and tube |
| Sample path | Sanitary diaphragm valve on the loop, cooler, sanitary outlet valve, no hose |
| CIP / SIP | Steamed from the loop side; pure steam version sterilizes itself every sample |
Common FAQs
0.5 to 2 gpm for a minute or two per sample, which no loop notices. The sample valve is located so the take-off is a short branch with no dead leg.
No. Each point has its own cooler so a sample cannot be contaminated by another point's water.
Yes, for the same reason a loop cooler does: tower water on the shell must not reach the sample through a tube joint. The gap is small but open and visible.
20 to 25 C for water samples, below 30 C for pure steam condensate: cold enough to bottle safely, warm enough that the outlet does not sweat onto the port.
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