SWEP B400T

The SC build - 316/316L plates with copper braze - is the general-duty construction: treated water, glycol mixes, oils and the common refrigerants all sit comfortably on it, up to the copper braze ceiling of roughly 185 C.

Three fluids rule it out. Ammonia attacks the copper. Deionized or ultrapure water leaches copper out of the joints and contaminates the loop before it weakens the unit. Chloride-bearing water - pool, brackish, seawater or heavily chlorinated tower water - pits 316 plate. The first two want a copper-free construction and the third wants SMO 254 plate, so name the fluid on both sides when you ask; the materials page sets out the codes.

It is the pressure class, and it is a category, not the stamped rating of your unit. S is the 31 bar at 155 C class used across a wide variety of applications; M runs up to 45 bar at 135 C and is fatigue tested, which is why it turns up on refrigerant duty such as R410A. Match the letter on the old nameplate - an S build in place of an M unit gives away pressure margin the circuit was designed around.

Do not rely on draining. A brazed pack does not empty the way a pipe does, and a two-pass side holds water in the turn between passes however the unit is tilted. Water left in a 0.403 dm3 channel that freezes can split the plates, and a brazed unit that has split is replaced, not repaired.

If either stream can see sub-freezing conditions, protect it with glycol at a concentration chosen for the lowest temperature the plate surface will see, and keep flow proven before the cold side is allowed to run. Size the unit on the actual glycol mix - it is more viscous than water, so pressure drop rises and heat transfer falls.

The B400T is the single-phase workhorse on the 694 x 304 mm plate, and the catalogued 2P1P arrangement points it at liquid-to-liquid duties where the two flows are far apart - heat recovery, process heating, storage charging.

It is the wrong choice for a chiller evaporator. The P400T, S400T and V400T share the same plate dimensions and 365.44 GPM ceiling but are built as evaporators, and a plain B-pattern unit in that position gives up performance. It is also wrong where two refrigerant circuits share one water stream: that is what the True Dual models such as the DB400 and DP400 are for, at a slightly lower 334.62 GPM.

Too few plates shows up first as pressure drop. The pump runs out of head, flow falls short of design, and the outlet temperature misses because the approach was never achievable on that surface. On a 2P1P pack the two-pass side is the one that complains first, since its fluid travels the plate length twice.

Too many plates is quieter but not harmless. Channel velocity drops, the turbulence that keeps the surface clean fades, and fouling settles in sooner. Control also gets coarse, because a small valve movement swings the outlet temperature. Between the 50 and 230 plate builds on file there is room to land the selection properly, so give the real flows and temperatures instead of rounding up.

Depth and port position. The face dimensions and the 601 x 205.50 mm port centres are fixed by the frame, but the pack gets deeper with every plate, so a replacement with a different plate count moves the rear face and anything piped to it. The builds on file run from 50 to 230 plates, and a 230-plate unit works out at about 163 kg (359 lb) on the published formula.

Then check which ports are used. On a multi-pass arrangement connections can sit on the back cover as well as the front, so a unit with the right footprint and the wrong pass arrangement will not meet the pipework.

These models are catalogued alongside the B400T. Each has its own page with its dimensions, materials and part numbers.

SWEP DB400 - True Dual brazed plate condenser for flexible chillers and climate control, 694 x 304 mm.

SWEP DP400 - True Dual brazed plate evaporator for flexible chillers and climate control, 694 x 304 mm.

SWEP DS400 - True Dual brazed plate evaporator with two refrigerant circuits, 694 x 304 mm, up to 282 plates.

SWEP DV400 - True Dual brazed plate evaporator, 694 x 304 mm, up to 282 plates, Victaulic and solder connections.

SWEP P400T - Copper-brazed 316/316L evaporator on the B400T frame, up to 280 plates, 365.44 GPM max flow.

SWEP S400T - High-capacity chiller evaporator on the B400T frame, 316/316L plates, copper brazed.

SWEP V400T - Copper-brazed 316/316L plate heat exchanger on the B400T frame for high-capacity chiller duty.

SWEP DB500 - True Dual brazed plate condenser with two refrigerant circuits, 980 x 304 mm, up to 298 plates.

SWEP DS500 - True Dual brazed plate evaporator with two refrigerant circuits, 980 x 304 mm, up to 298 plates.