SWEP B4T

The catalogued B4T on file is a single-pass unit - the /1P in B4THx50/1P-NC-U - and SWEP's own example designation for the model is 1P as well. In a single-pass build all four connections are on the front cover and each fluid crosses the plate length once.

If a nameplate shows anything other than 1P, treat it as a different exchanger: the thermal length, the pressure drop and the port layout all change. Send the full designation and we will confirm what can be supplied. The Model Number Guide shows where the pass code sits in the string.

SWEP publishes PED, UL and KHK for the B4T. PED is the European pressure equiptment route, UL is the North American listing most refrigeration inspectors look for, and KHK covers Japanese high-pressure gas rules.

The practical point is on CO2 duty. The catalogued B4T is a U-class build, and UL approval for CO2 wants a relief valve on each side set at 0.9 times design pressure. A unit piped without those valves does not meet the listing it was bought for. The approval that applies to a specific unit is the one stamped on its nameplate, so name the approval you need when you ask for a quote.

Yes, whenever the refrigerant side can run below the freezing point of the liquid side. The B4T has very little liquid in each channel, so it freezes quickly, and ice in a brazed channel can split the plate pack. A unit that has frozen usually shows up as refrigerant in the water circuit or water in the refrigerant circuit.

Glycol lowers the freezing point but also raises viscosity and pressure drop, so the exchanger has to be rated on the actual mixture, not on water. Add a flow switch and a low-temperature cutout as well. See Freeze Protection for the full list.

The datasheet allows up to 100 plates. The part number on file is a 50-plate unit. Adding plates adds paralell channels, which lowers pressure drop on both sides and tightens the approach temperature for the same flow.

It does not raise the 5.28 GPM port ceiling - that is fixed by the port size. Weight follows the published formula of 0.48 + 0.04 kg per plate, so a 50-plate B4T is about 2.5 kg (5.5 lb) and still hangs comfortably on its own pipework brackets.

Undersized, the B4T runs with a wide approach and a high pressure drop: the pump or compressor works harder and the leaving temperature never reaches setpoint. With a capacity range that tops out at 30 kW and a 1.2 m3/h port limit, it is easy to ask too much of this frame, and the answer is a larger frame, not more plates.

Oversized is the quieter problem. Too many plates for a small refrigerant flow gives low channel velocity, poor distribution across the pack and oil that does not return. On the liquid side low velocity lets dirt settle. Size to the real duty rather than the nearest round plate count.

These models are catalogued alongside the B4T. Each has its own page with its dimensions, materials and part numbers.

SWEP B4 - The smallest frame in the range, and one of the three rated for transcritical CO2.