1-805-484-2992
Quotes - Engineering - SalesReceiving, farm and silo
The first exchanger the milk ever sees
Raw milk leaves the cow at 100 F and has to be at 45 F within two hours and at 40 F or below to keep its count down. On a farm that is a plate precooler on well water ahead of the bulk tank. At a plant it is a receiving cooler that takes tanker milk at 38 to 60 F into the silo at 36 to 38 F, or a silo loop cooler that pulls the silo back down after a warm load.
None of these duties involve heating, holding or regulation. They are pure cooling on a thin fluid, decided by the utility, the peak load and the plate gap.
Sizing for the water you have and the load you will see
Farm precoolers on well water
A farm milking 300 cows delivers milk at 98 F at 10 to 15 gpm, and the bulk tank compressor is sized on the temperature it receives. A single-section plate cooler on 55 F well water at twice the milk flow brings the milk to 60 to 62 F and cuts the tank's refrigeration load by more than half. The water leaves at 70 to 75 F and goes to the stock waterers, which is why the ratio stops at two to one.
Sizing is done on the warmest well water of the year and the fastest milking. A second section on chilled water from the tank's own condensing unit can land 40 F before the tank. The unit is 10 to 30 plates on a small frame.
Receiving bay coolers
Tanker milk arrives at 38 to 45 F in winter and up to 60 F after a long haul in August. The receiving cooler sees the whole tanker at pump rate, 200 to 400 gpm for 20 minutes, then nothing until the next one. It is sized on 60 F milk in, 34 F chilled water at 2.5 times the milk flow; on the winter tanker it loafs.
The peak surprises people. Cooling 400 gpm from 60 F to 37 F is about 4 million Btu/h, 330 tons of refrigeration, for 20 minutes. No plant has that idle, so an ice bank or chilled water tank carries the peak and the cooler is sized for the water temperature at the end of the pull. A tower water first section takes 20 to 30 percent off the chilled peak. Cooling duties further along the plant, from the pasteurizer outlet to filled product, are covered on our dairy cooling pages.
- Size on the August tanker and end-of-pull chilled water
- Tower water first section where it runs under 70 F
- Frame with 20 percent spare plate room
Silo loops and 36 F
A silo at 38 F takes a warm tanker and drifts to 41 F. The loop cooler pulls the silo through a plate cooler and back, 100 to 200 gpm at a 2 to 3 degree drop per pass, for an hour after each warm load. Getting to 36 F rather than 38 F needs glycol, because 34 F chilled water cannot hold a 3 degree approach on a big load. Plants that want the extra two days of raw milk life put the silo loop on glycol and keep the receiving cooler on chilled water.
The common mistake
Sizing the receiving cooler on the average tanker and the morning chilled water temperature. The cooler lands 37 F all winter and 43 F on the third tanker of an August afternoon when the ice bank is spent, and the silo count climbs. HeatX sizes on 60 F milk and the chilled water temperature at the end of the plant's worst hour; if the plant does not know that number, it is the first question to answer.
Send the tanker pump rate, the warmest milk you receive, the water available and the silo temperature you want. Call and talk it through with an engineer: 1-805-484-2992
Raw milk cooling process conditions
This table sets out what a farm precooler, a receiving bay cooler and a silo loop are each sized for, and the utility behind each. Find the closest case to yours and send the milk and water you actually have.
| Condition | Detail |
| Product | Raw whole milk, 3.5 to 4.5 percent fat, 2 cP at 70 F |
| Flow range | Farm 5 to 60 gpm; receiving bay 100 to 400 gpm; silo loop 50 to 200 gpm |
| Temperatures in / out | Farm 98 F to 60 F on well water; bay 40 to 60 F in, 36 to 38 F out |
| Hold | None; single pass, seconds of residence |
| Utility | Well water at 50 to 60 F; tower water; chilled water at 34 F; glycol for 36 F |
| Approach | 3 to 5 degrees chilled water to milk; 5 to 8 on well water |
| Construction | Gasketed plate, one or two sections; straight tube where brushable |
| Finish / class | 3-A plates, 316L, 32 Ra, nitrile or EPDM gaskets |
| Pressure | Product 50 to 100 psig; utility 100 psig with well pumps |
| CIP | Daily on the farm; each shift at the plant |
Common FAQs
About 2 gallons of well water per gallon of milk on a farm precooler, 2 to 2.5 gallons of chilled water on a receiving cooler. Less water means more plates; beyond 3 to 1 gains almost nothing.
Not unless the well is under 38 F. Well water at 50 to 55 F gets milk to 58 to 62 F; the bulk tank or a chilled section does the rest.
Plate, almost always. Raw milk is thin and clean, the duty is large, and plates give the cheapest area. Straight tube is used where the plant wants a brushable unit or the milk carries fines.
At the tanker pump rate, in one pass. A tanker that takes 20 minutes to unload should be in the silo at 36 to 38 F in those 20 minutes.
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