SWEP P400T

The published example designation, P400TH/1P-SC-M, is a single-pass build, and that is what an evaporator duty normally calls for. The pass arrangement is the figure after the slash in the designation.

A multi-pass build sends a fluid through the plate pack more than once. That lengthens the thermal path and tightens the approach, but it raises pressure drop and typically moves some connections to the rear cover plate, so the piping changes with it. On a replacement, read the pass figure before anything else: a 1P unit will not stand in for a multi-pass unit without repiping and a new rating.

Vertically, with refrigerant and water running counter-current. Two-phase duty needs the plates upright so liquid and vapor spread across the channels; a unit laid on its side floods some channels and starves others, which shows up as unstable superheat and a capacity shortfall that no valve adjustment cures.

Counter-current piping gives the closest approach, so a water side connected backwards still runs but delivers warmer leaving water than the design. At the full 280 plates the published weight formula gives about 211 kg (466 lb) dry, so carry the body on its own support and hang the piping independently - the connections should take no load. See Mounting and Piping.

The P400T, S400T and V400T are all evaporators on the same 694 x 304 mm frame with 316/316L plates, copper braze and a 365.44 GPM max flow. SWEP describes the P400T by its specially developed plate pattern and long thermal length, for chillers, heat pumps and economizers; the S400T and V400T are described as high-capacity evaporators for demanding chiller applications.

The DP400, DS400 and DV400 are True Dual evaporators and the DB400 a True Dual condenser. They share the outline but carry a lower 334.62 GPM max flow and are a separate product for flexible chillers, not a substitute for a P400T.

The full designation off the nameplate: model and plate type letter, plate count, pass arrangement, material code, pressure class and the connections in port order. The SWEP article number, if legible, settles it faster than anything else.

If the plate is unreadable, send A x B, the port centres, the depth of the plate pack, the plate count taken from the edge of the pack, and the type and size of each of the four connections. Add the refrigerant, the capacity, the evaporating temperature and the water flow and temperatures so we can check the selection against the duty. Send it through Request a Quote.

Too few plates and the evaporating temperature has to drop to make the capacity. Suction pressure falls, the compressor loses capacity and efficiency, water pressure drop climbs, and the plate surface runs closer to freezing.

Too many plates is the less obvious mistake. Refrigerant velocity per channel falls, distribution across a wide pack gets uneven at part load, oil return suffers and the expansion valve hunts. With up to 280 plates available on this frame there is room to land in between - size it to the duty rather than adding plates as a safety margin.

These models are catalogued alongside the P400T. Each has its own page with its dimensions, materials and part numbers.

SWEP B400T - Asymmetric pass arrangement - two passes one side, one the other.

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 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.