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SIP makes condensate at 250 F, and the drain, the sample point and the floor all have limits
A steam-in-place cycle pushes clean steam through a vessel or a line, and every trap, barrier and low-point drain discharges condensate at 250 to 275 F, which flashes the moment it sees atmospheric pressure. Clean steam condensate is not returned to a boiler; it goes to drain through an air gap, and plumbing codes stop the drain at 140 F. The trap discharge from a 2,000 liter bioreactor SIP is several hundred pounds per hour of water that will scald and soften a plastic drain line if nothing cools it.
The parent page covers the generator and barriers. This page is about the small exchangers on the way out: the drain cooler, the blowdown cooler, and the sample cooler that turns 275 F steam into a 77 F sample the conductivity meter can read.
Coolers on the condensate side of a clean steam system
Drain coolers and the flash load
Condensate at 250 F dropped to atmospheric pressure flashes about 13 percent of its mass to steam, at 275 F about 16 percent. A drain cooler therefore sees a two-phase inlet, and a unit sized on liquid alone passes live steam to the drain. HeatX sizes on condensate plus flash: 1,000 lb/h of 250 F condensate to 130 F is about 250,000 Btu/h, with the flash condensing in the top of the shell and the liquid subcooling below it. City water at 60 F once through needs about 60 gpm for that duty; tower water needs more area.
On a large SIP header a flash tank ahead of the cooler vents the flash and sends only liquid on, which halves the cooler. The condensate line to the cooler is stainless; the drain after it can be whatever the plant has. Condensing SIP steam before it reaches the drain is covered on our SIP clean steam condenser page.
Blowdown cooling on the generator
Continuous blowdown leaves the generator shell at 280 to 300 F at 5 to 10 percent of the steam rate. The same drain limit and flash arithmetic apply, plus one thing: blowdown carries the concentrated feedwater solids, so the blowdown side is 316L on the shell of a small straight-tube unit with a low-point drain, and a plant with a hot water demand runs it against the feedwater or CIP make-up rather than to waste.
- Blowdown on the shell, cooling water in the tubes, 316L both sides on pure steam generators
- Outlet under 140 F, or under 120 F where the plant wants margin on the drain
- Feedwater preheat as the sink where the arithmetic allows it
Sample coolers for steam and condensate testing
Steam quality and condensate purity are proven on a cooled sample. A sample cooler is a 316L coil in a small shell, sample in the coil at full system pressure, chilled water on the shell, delivering 77 F, the temperature the USP conductivity and TOC methods are referenced to and one a technician can hold a bottle under. A cooler on tower water in August delivers 95 F and the stage-one conductivity reading is invalid. The coil is electropolished where the sample feeds a TOC analyzer, and the cooler is steamed between samples.
Sample points sit at the generator outlet and at the farthest use point; the sampling condenser the parent page describes feeds the same sample cooler.
The common mistake
Sending SIP condensate to the floor drain through a PVC line because the trap outlet is small. The first 30-minute cycle softens the pipe at the first elbow, flash fills the room, and someone is scalded reaching the valve. The trap discharge goes to a stainless header, through a cooler sized on condensate plus flash, and to the drain under 140 F through an air gap. Call and talk it through with an engineer: 1-805-484-2992
SIP condensate cooling conditions
Condensate leaves a sterilizing header hot and often flashing, and it has to reach the drain or the sample point cooled. Compare the rows with your header and send both flow and drain limit with the quote request.
| Condition | Detail |
| Fluid | Clean steam condensate from traps, barriers and drains; generator blowdown; steam samples |
| Flow range | 50 to 2,000 lb/h condensate during SIP; 0.25 to 2 gpm on a sample cooler |
| Temperatures in / out | 250 to 275 F in with flash; under 140 F to drain; 77 F on samples |
| Hold | None; a flash tank ahead of the cooler on large SIP headers |
| Utility | City or tower water on drain coolers; chilled water on sample coolers |
| Approach | 20 degrees on a drain cooler; 5 degrees on a sample cooler |
| Construction | Straight tube or U-tube, condensate on the shell; sample cooler is a coil in a small shell, sample in the coil |
| Finish / class | 316L condensate side, 32 Ra; sample coil 316L electropolished where the sample goes to TOC |
| Drain limit | 140 F by most codes; 120 F where the plant sets margin |
| CIP / SIP | Drain coolers steamed with the header; sample coolers steamed between samples |
Common FAQs
A tempering valve works on a small trap and wastes water; on a header discharging 1,000 lb/h with flash it takes 60 gpm continuously and still passes steam when the valve lags. A cooler is controllable and can recover the heat.
No. It has been in contact with product-side surfaces and it is not the boiler's water. It goes to drain through an air gap, cooled below 140 F, or to a reuse point such as CIP make-up where the plant allows.
A 316L coil rated for full clean steam pressure in a small shell on chilled water, delivering 77 F at the tap. Electropolished where the sample feeds TOC, steamed between samples, and mounted where the technician can reach it.
About 13 percent by mass at atmospheric pressure, rising to about 16 percent from 275 F. The flash carries roughly a third of the heat, so a cooler sized on liquid alone is a third short.
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