SWEP B85S

Too small, and it shows as high pressure drop and a condensing or leaving temperature that will not come down: the compressor runs at a higher head pressure, or the process stream leaves warmer than specified. The plate pack is working at its limit and adding flow only adds pressure drop.

Too large is harder to spot. Channel velocity falls, and on a shallow-pressed plate that means poorer distribution across the pack and more opportunity for solids to settle. On refrigerant duty, oil return suffers. The B85S is an efficient plate, so it needs fewer plates than an older design for the same duty - copying the old unit's plate count usually oversizes it.

When the design flow on either side approaches the published 17 m3/h (74.85 GPM). That figure is the port ceiling, not a recommended operating point. Near it, port velocity and port pressure drop dominate, and no number of plates fixes that.

The B85S goes to 160 plates, so there is a wide range of capacity available before the ports become the limit. If a selection needs the full plate count and still shows a pressure drop the pump or the refrigerant circuit cannot carry, move to a larger frame with bigger ports. Pressure Drop explains how to read the split between ports and channels.

Per channel, a shallower pressing means a smaller channel, and SWEP states the B85S has a smaller pressing depth than previous generations. SWEP publishes the same per-channel volume on both sides of the B85S; multiply it by the channels on the refrigerant side, about half the plate count, to get the hold-up.

On a condenser that matters twice. Less internal volume means less refrigerant charge, which counts on ammonia systems and wherever charge limits apply. It also means less liquid stored in the condenser, so the receiver and the subcooling control have to be sized for the system rather than relying on the exchanger as a buffer.

The nameplate designation in full, or the SWEP article number. A B85S designation carries the plate type, plate count, pass arrangement, material code and pressure class - SWEP's example reads B85SH/1P-SPS-M - followed by the connections.

Where the nameplate cannot be read, send the outline and port-centre dimensions, the plate count, and the connection type on each port, saying whether they are threaded or Victaulic. Add the two fluids, their flows and the inlet and outlet temperatures. For a new duty rather than a replacement, the fluids, flows, temperatures and allowable pressure drops are enough for us to select the plate count and confirm it with the quote.

These models are catalogued alongside the B85S. Each has its own page with its dimensions, materials and part numbers.

SWEP B85 - 160 plates on the 526 mm frame, with tighter channels than the B80.

SWEP F85 - A compact copper-brazed plate heat exchanger with large ports for high-performance condensers.

SWEP F85AS - AsyMatrix evaporator on the 85 platform with integrated distribution for high-pressure refrigerants.