1-805-484-2992
Quotes - Engineering - SalesRead the product, then pick the channel
Every construction we build trades heat transfer against what the channel will tolerate. Gasketed plates give the highest film coefficient and the smallest footprint, but their 3–5 mm channels and touching contact points suit only thin, clean product. Opening the channel to a wide gap buys tolerance for fat and viscosity. Moving to tube-in-tube buys tolerance for pieces and shear. Straight tube buys a bore that a cleaning crew can brush.
The short version
Stated as a rule: gasketed plate on water-like milk, wide-gap plate on cream above about 30% fat and on ice cream mix, tube-in-tube once cultured product has broken or pieces are in the stream, straight tube when the plant must brush it, and shell-and-tube for UHT and high pressure. Applying the rule means knowing the product at its coldest point inside the exchanger, not as it sits in the tank.
Viscosity is set at the cold end. Cream that pours easily at 120°F can be several times thicker at 40°F, and that is where a plate starts to channel and foul first.
Construction by product
- Skim, whole, low-fat and flavored milk: gasketed plate, 3–5 mm gap
- Clarified whey and permeate: gasketed plate
- Cream above about 30% fat and ice cream mix: wide-gap plate, 6–12 mm
- Yogurt and cultured product after the break: corrugated tube-in-tube
- Fruit preparation with pieces up to about 1 in: single-tube
- Product side brushed by hand: straight tube
- UHT and high pressure: shell-and-tube or tubular
Wide-gap plate channelDoubling or tripling the standard channel lets cream and mix pass the contact points without bridging, at some cost in film coefficient and pack length.
Signs the construction is wrong
When a plant calls about an exchanger that never met its rating, the cause is often a construction mismatch rather than too little surface. The symptoms are easy to recognize once you know them:
- Pressure drop climbing through the shift on a cream or mix heater
- Product leaving the cooler thinner than the lab standard
- Fruit pieces arriving broken, or ports and distribution areas plugging
- CIP leaving a fat film at plate contact points
- Run length between cleans much shorter than on the plant's other units
Call and talk it through with an engineer: 1-805-484-2992
Where the lines blur
Between milk and heavy cream there is a gray zone. Half-and-half and light cream, roughly 10–30% fat, will run in standard plates if the cold end is not too cold and the plant accepts a higher pressure drop. We size these on the standard plate first and move to a wide gap only when the predicted drop or the fouling margin says so.
Ice cream mix is less forgiving. With 36–40% total solids, stabilizers and sugar, it sits firmly in wide-gap territory for heating, and many mix plants switch to tubular for the final cooling where viscosity peaks. A wide-gap plate for cream and mix still wins on footprint and on regeneration where the plant has room for neither a long tubular run nor its hold-up volume.
Cultured product turns on the break. Before it, the milk base is thin enough for plates, and a plate section heating it to 185–195°F is common. After it, the curd is a gel that recovers poorly from shear. Corrugated tube-in-tube, with a generous annulus and gentle velocity, cools it without losing body.
Straight tube and shell-and-tube are chosen for reasons beyond the product itself. A plant that inspects and brushes every tube after a run, a UHT line at 275–300°F with the pressure that brings, or a product with heavy burn-on all push toward a construction that a gasket cannot match. The longer plate-versus-tubular comparison for HTST lines is set out on our sanitary process page for plate and tubular HTST, if you want the background behind these rules.
Size for the coldest point in the exchanger, not the tank temperature.
Send the product, its fat percent and its coldest temperature in the unit, and the construction usually picks itself.
Request a QuoteSelection questions
Usually, for heating and for moderate cooling. A wide-gap pack keeps a higher film coefficient than an annulus, so it needs less surface and less floor, and it can carry a regeneration section. Tubular pulls ahead when the cream is cooled very cold, where pressure drop through plates climbs fast, or when the plant wants no gaskets at all on that duty.
In a single-tube unit the limit is the bore, and dairy fruit preparations with pieces up to about 1 in are normal. Multi-tube and corrugated designs have smaller passages and suit smooth or broken-curd product rather than whole pieces. Send the largest piece dimension and its fraction of the stream; a few large pieces matter more than many small ones.
Because on thin milk a tubular unit needs several times the length for the same duty, holds more product at changeover, and recovers less heat in a sensible footprint. Gasketed plates earn their place on fluid milk; gaskets are a maintenance item, not a reason to give up regeneration and floor space on the plant's biggest duty.
Sometimes. If the carrying bars have spare length and a wide-gap pattern exists for that frame size and port, new wide-gap plates can form their own section behind a connector plate. Otherwise a separate frame is cleaner. We check frame length, port size and the plate pattern before offering it, and we supply the plates and gaskets new.
Yes. Plate exchangers are covered by the 3-A plate standard, current edition 11-10, and tube-in-tube and shell-and-tube units by the tubular standard, current edition 12-08. Each sets its own rules for drainability, access and product-contact surfaces, so a construction change on a 3-A line also changes which standard the inspector reads it against.
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