SWEP B250AS

It is the most the ports will pass, 62 m3/h, and not a flow to design at. Real selections sit below it, and the plate count decides how far below.

The asymmetry adds a point. The two channel sets hold 0.172 and 0.202 dm3, so at equal flow the two sides do not see the same pressure drop. The port ceiling says nothing about that, so the selection has to be run with the fluids on the correct sides.

Our catalogued builds run from 50 to 228 plates against a 300-plate maximum. If the water side needs more than that to meet its pressure drop allowance, the duty belongs on a larger frame such as the B400T.

Isolate the water side and circulate a cleaning solution through it in the reverse of normal flow, using a cleaner that is safe for copper braze and stainless. Then flush thoroughly. The refrigerant side stays sealed.

Pump the refrigerant charge out of the exchanger first, or at least make sure the compressor cannot start. Water-side flow stops during cleaning, and an evaporator that keeps running with no water flow freezes.

The published particle limit is 0.8 mm. A strainer finer than that keeps debris out of the channel entries. On an evaporator, a plugged channel is more than a capacity loss, because that is where ice forms first.

The approvals cover the exchanger as a pressure part: PED, UL and KHK, on a build in the H pressure class. They confirm the unit is rated for the pressure and temperature on its nameplate.

They do not cover the system-level requirements for flammable refrigerants. Charge limits, leak detection, ventilation and the equipment listing are settled for the machine as a whole.

For a replacement, match the pressure class letter on the old nameplate.

Slightly more exposed, and for the same reason it is specified. A pack designed for low hold-up contains less water per plate, so there is less thermal mass to absorb a loss of flow or a sudden unloading before ice forms.

Glycol lowers the freezing point and is the reliable fix for low leaving temperatures. It also costs capacity and pressure drop, so the unit must be selected on the actual mixture.

On plain water the protection is controls: proven flow before the compressor starts, a leaving-water freeze limit, and a suction pressure cutout. Reversible machines need this in both modes, including defrost. See freeze protection.

It is right on refrigerant-to-water duty where charge and pressure drop both matter: large evaporators and condensers on chillers and heat pumps, in the H pressure class.

It is wrong wherever copper or 304 is wrong. The AS means asymmetric channels, and the build is 304 plate with copper braze, so ammonia, deionized water and chloride-bearing water are all out. It also gains little on a balanced water-to-water duty, where a symmetric frame is the simpler choice.

Check the prefix on a nameplate as well. F250AS and P250AS are single-circuit evaporators for reversible chillers built on the same 620 x 202 mm plate, and they are different products from the B250AS.

These models are catalogued alongside the B250AS. Each has its own page with its dimensions, materials and part numbers.

SWEP F250AS - A copper-brazed single-circuit AsyMatrix evaporator for reversible chillers.

SWEP P250AS - A copper-brazed 304 stainless single-circuit AsyMatrix evaporator for reversible chillers.