1-805-484-2992
Quotes - Engineering - SalesBetween the make-up tank and the bioreactor
Heating to dissolve, cooling to use
A buffer suite makes 500 to 10,000 liter batches of phosphate, Tris, acetate or citrate on WFI; a media suite makes basal media with glucose, amino acids and salts. Both are made warm because powders dissolve faster at 30 to 45 C, and both are used cold: chromatography buffers at 18 to 22 C or 2 to 8 C, media at inoculation temperature. The exchanger sits on the transfer line and does the temperature change in-line rather than in the tank.
The catch is the fluid: concentrated buffers are 1.5 to 3 cP and dense, media with surfactant foams at the first vortex, and both go on to a sterile process.
Viscosity, foaming, salt and the cold end
Buffers are not water
A 1 M phosphate buffer is about 1.6 cP at 20 C and 2.5 cP at 5 C; 2 M ammonium sulfate for hydrophobic interaction chromatography is over 3 cP cold at 1,130 kg/m3. The tube-side coefficient falls and the pressure drop rises as the buffer chills, and an exchanger sized on water at 50 gpm delivers a 2 to 8 C buffer at 12 C on the coldest day. HeatX sizes on the actual buffer at the outlet temperature and quotes the pressure drop cold so the transfer pump is chosen against the real number. Concentrated buffers also crystallize: 2 M ammonium sulfate drops salt below about 4 C, and a cooler that overshoots on -5 C glycol plates salt onto the tubes.
Media foams, and the exchanger can make it worse
Media with a poloxamer or similar surfactant foams at any air-liquid interface under shear. Inside the exchanger the flow is full-bore and foam is not the issue; the issue is entrained air arriving from a prep tank mixed too hard, and a free-fall outlet into a hold tank. Air in the tubes cuts the coefficient and on a plate blankets channels so part of the plate does nothing. The fix is outside the exchanger: mix without a vortex, take the transfer from the bottom outlet, run a back pressure valve at the exchanger outlet so it stays liquid-full, and enter the hold tank through a bottom or tangential nozzle. Product goes on the tube side, or in the wider channel of a double-wall plate, where the velocity is smooth.
Media is made on WFI and goes to a sterile process
Basal media leaves the prep tank and either goes through a sterilizing filter or through a continuous sterilizer at 121 C. Either way it is a WFI-based product against plant utility water on the other side of a tube, and the double tubesheet applies. Buffers used in chromatography are also WFI-based, but many sites accept a double-wall gasketed plate on a clear buffer because the plate opens for inspection and the double wall shows a leak. The distinction HeatX draws at quote time is whether the exchanger outlet is inside a sterile boundary: if it is, the unit is double tubesheet, SIP-rated and welded on the product side; if the filter is downstream, the double-wall plate is acceptable and cheaper.
The common mistake
Sizing the cooler for the average transfer and fitting it to a hold tank that cannot wait. A 5,000 liter batch at 50 gpm takes 26 minutes; the cooler has to bring every liter from 35 C to 6 C at 50 gpm from the first liter, because a jacketed hold tank at 2 to 8 C will not pull a 15 C batch down before the column needs it. Size on the transfer rate at the cold outlet with 20 percent margin, on glycol, with a small approach, and size the pump on the cold pressure drop.
Send the composition and concentration, batch size, transfer time, temperatures and utility, and the cooler is sized on the real fluid. Call and talk it through with an engineer: 1-805-484-2992
Buffer and media prep process conditions
These rows describe the buffer and media prep exchangers we quote, from foaming behavior to the clean and sterilize cycle. Set them beside your batch process and send your volumes and temperatures with the request.
| Condition | Detail |
| Product | Buffer salts and media in WFI, 0.05 to 2 M, with or without surfactant; 500 to 10,000 L batches |
| Flow range | 10 to 100 gpm; sized to empty the make-up tank in 30 to 60 minutes |
| Temperatures in / out | Heating 20 to 40 C for dissolution; cooling 40 C to 18 to 22 C or to 2 to 8 C |
| Hold | None; the jacketed hold tank is downstream |
| Utility | Chilled water 7 C or glycol -5 C on the cooler; 90 C hot water on the heater |
| Approach | 3 to 5 C on 2 to 8 C duties, which means glycol below 0 C on the shell |
| Construction | Double tubesheet shell-and-tube for media; double-wall gasketed plate for clear buffers |
| Finish / class | 316L, 15 to 20 Ra electropolished, ASME BPE; EPDM or platinum-cured silicone gaskets |
| Foaming | Product on the tube side, full-bore connections, back pressure valve at the outlet |
| CIP / SIP | CIP with the transfer line; SIP at 121 C ahead of a sterile hold |
Common FAQs
A 5,000 liter jacketed tank cools 30 C in three to five hours; an in-line cooler does it on the 30 minute transfer.
High-concentration ammonium sulfate, some phosphates above 0.5 M, and citrate near saturation. The glycol temperature is set to keep the wall above the crystallization point.
Yes, on a hot water and glycol header with a changeover valve. The unit is sized for the cooling duty, which is the harder one.
Many sites accept a double-wall plate ahead of a sterilizing filter and require double tubesheet only inside the sterile boundary.
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