SWEP B30

They answer different problems. The B30 is a single-circuit cross-flow frame with a published ceiling of 58 m3/h (255.37 GPM), chosen when the two streams are far apart in flow. The DB310 is a true dual, built for chillers and heat pumps and optimized for refrigerant duty, with a ceiling of 264.17 GPM.

The flow figures are close enough to invite a substitution, and that is the mistake. A true dual has two refrigerant circuits against one water circuit, so the port count and the piping are different. Read the first letters on the nameplate before anything else: a D-prefix unit is not replaced by a B30.

Any water-filled channel that reaches freezing will split, and the B30 is no exception. Where it is used with refrigerant on one side - economizer or desuperheating service - the usual cause is not weather. It is refrigerant continuing to evaporate after the water flow has stopped, which freezes the standing water in minutes.

Glycol lowers the freezing point but does not make the unit safe by itself. Pair it with a flow switch or differential-pressure proof and a low-temperature cutout, and run the pump before the refrigerant side starts and after it stops. Tell us the glycol concentration at selection, since it raises pressure drop and trims capacity. More on the Freeze Protection page.

SWEP publishes 5.68 kg plus 0.171 kg per plate (12.53 lb plus 0.377 lb per plate). A 100-plate unit therefore weighs about 22.8 kg (50.2 lb) dry, and a full 301-plate pack about 57.2 kg (126 lb) before the water is in it.

The connections are brazed to the cover plate and are not structural. Put the B30 on a bracket or a shelf under the pack, support the pipes independently within a short distance of the ports, and leave the connections carrying nothing but fluid.

It is built for unequal streams. The channels are asymmetric, 0.105 dm3 on one side and 0.081 dm3 on the other, so a large flow and a small flow can each run at a sensible velocity instead of one side crawling while the other chokes.

It is the wrong frame in two cases. If both sides carry similar flows and the duty needs a close temperature approach, a counter-current parallel-flow frame does that better, because cross-flow gives up part of the temperature difference. And if the water is dirty, note the 0.9 mm particle limit, which is tighter than the 1 mm published for most frames in this band.

It means each fluid makes two passes through the plate pack instead of one. On a plate only 243.5 mm long, two passes are how the B30 gets a useful thermal length - a single pass across a plate that short gives a modest temperature change.

The cost is pressure drop, because the same flow goes through fewer channels in parallel and travels twice as far. In the same string, L2 is the acute chevron plate and H is the 45 bar at 155 C class.

These models are catalogued alongside the B30. Each has its own page with its dimensions, materials and part numbers.

SWEP DB310 - True Dual brazed plate exchanger for chillers and heat pumps, up to 350 plates, 264.17 GPM max flow.