SWEP B85

Pick it when the approach temperature is the hard part and the pump has head to spare. The 0.094 dm3 channels give high velocity and strong heat transfer from a 526 x 119 mm plate.

Leave it alone in two situations: an open or poorly filtered loop, because the 0.8 mm particle limit is tight; and a duty pressing toward the 17 m3/h (74.85 GPM) ceiling with a small temperature change, where the narrow channels turn flow into pressure drop without any benefit.

Clean water, glycol solutions, oils and the common refrigerants. The builds on file carry SC (316/316L plates) or NSC (316 channel plates with 304 cover plates), and both are copper brazed.

Keep ammonia out; it attacks the copper. Keep deionized and ultrapure water out; they dissolve copper from the braze and contaminate the loop. Chloride-bearing water pits 316. For the copper-free cases the B85S exists on the same plate size with stainless braze. Plate and Brazing Materials lays out which code suits which fluid.

The frame is published to 160 plates, and the catalogued builds run from 20 to 140.

Each added plate adds surface and one more channel in parallel. Capacity rises, the approach tightens and the pressure drop for a given flow falls. On the B85 that last effect is the useful one: a selection that works thermally but exceeds the pump head is often rescued by adding plates, without changing frame. The weight goes up by 0.1367 kg (0.301 lb) per plate and the pack gets deeper, so recheck the space behind the unit.

The B85 and B85S share the 526 x 119 mm plate and the 74.85 GPM ceiling. The B85S is the all-stainless version, with 316 plates and stainless braze, for systems that must be copper free or run hot.

The F85 and F85AS are not the same envelope. They are published at 524 x 117 mm, with 316 plates and 304 cover plates, copper brazed. The F85 is aimed at high-performance condensers and demanding heat transfer, and the F85AS adds AsyMatrix asymmetric channels for higher thermal performance at lower pressure drop. AS can also follow the B, as in the catalogued B85ASHx34/1P-NSC-M. In all of these it means AsyMatrix, never all-stainless.

Fine enough to stop 0.8 mm. That is tighter than the 1 mm published for the B80 and B28 on the same plate outline, and a strainer left in place from one of those is too coarse for a B85.

The narrow channels that give this frame its performance are also what catch debris. Early fouling shows as rising pressure drop with the leaving temperature still on target, and at that stage reverse flushing clears it.

M is the class for refrigerant service: up to 45 bar at 135 C, fatigue tested, intended for refrigerants such as R410A. All the catalogued B85 builds on file carry it.

Two points on using it. The letter is a category; the stamped figures on the nameplate are the rating that governs the relief valve setting and the inspection. And the temperature side of the class is the lower one - S class trades pressure for temperature at 31 bar and 155 C. A hot-water or hot-gas duty above 135 C is outside M even when the pressure is modest. If your nameplate ends in another letter, call for rating. See Pressure Classes.

Circulate a cleaning solution suitable for both stainless steel and copper through the fouled side, in the opposite direction to normal flow, using a separate pump and tank. Finish with a thorough flush until the water is neutral.

With channels this narrow, timing matters more than on a wider-channel frame. Clean when the pressure drop has risen noticeably. Once channels are fully blocked the solution bypasses them through the open ones, and the blocked channels stay blocked. Fitting valved tees at the ports during installation makes it a short job later.

These models are catalogued alongside the B85. Each has its own page with its dimensions, materials and part numbers.

SWEP B85S - An All-Stainless, high-efficiency brazed plate heat exchanger with large ports.

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.