SWEP B8T

It names the pressure class. M is the category rated up to 45 bar at 135 C and fatigue tested, the class normally chosen for refrigerant duty. Every catalogued B8T string on file ends in M, as does the datasheet example B8TH/2P-SN-M.

Treat the letter as a category and the nameplate as the rating. The stamped design pressure and temperature on the unit you are replacing are what the new one has to meet. One trap on this frame: nickel braze raises the metallurgical ceiling to around 350 C, but that does not turn an M-class unit into a high-temperature vessel. The class still sets the limit. More on Pressure Classes.

Usually enough. Any surviving fragment of the string helps - "B8TH", an "x20", an "SC" or "SN", the final class letter - and so does the article number if it is legible.

What the plate will not give you, the unit will. Count the plates along the edge of the pack. Measure the plate at 317 x 76 mm and the port centres at 278 x 40 mm to confirm the frame. Then look at the braze fillets between the plates: copper braze shows a copper color, nickel a gray one. That matters here because the datasheet build is nickel brazed (SN) while the catalogued strings on file are copper brazed (SC).

Three things: the plate face, the port centres and the pack depth. The face is 317 x 76 mm (12.48 x 2.99 in) and the ports sit on 278 x 40 mm centres (10.94 x 1.57 in). Those are fixed for the frame. Depth is not - it grows with every plate, so measure the thickness of the existing pack and give us the plate count.

Measure carefully, because the look-alikes are close. The E8T and BX8T are 315 x 73 mm and the double-wall B8DW is 318 x 76.5 mm. A tape held loosely will not separate them, and their ports will not line up with rigid pipework. Note also which connections are threaded and which are solder, in port order.

Keep flow moving whenever the cold side can pull the water side below freezing, and dose glycol for the lowest temperature the plate surface can reach, not the lowest loop temperature. Each B8T channel holds only 0.039 dm3, so a stalled channel freezes in moments, and ice in a brazed pack splits it. There is no repair for that.

Glycol is not free. It is more viscous and carries less heat than water, so the same unit delivers less capacity at a higher pressure drop. Give us the glycol type and concentration with the duty. See Freeze Protection.

Very little. SWEP publishes 0.039 dm3 per channel on both sides. A 20-plate unit has 19 channels, split ten and nine, so it holds about 0.39 liters on one side and 0.35 on the other.

That keeps a refrigerant charge down and makes the unit respond within seconds, with no thermal buffer. A control valve that is oversized or tuned for a storage-type exchanger will hunt on a B8T, so tune the loop for a fast device.

Too little surface on the duties this frame is bought for usually means a process stream that will not reach its outlet temperature, and the temptation is to push more flow. That raises pressure drop steeply and still does not close the gap, because the frame tops out at 17.61 GPM (4 m3/h) on its ports.

Too much surface is the less obvious failure. Adding plates divides the flow across more channels, and with small ports feeding a long pack the outer channels see less flow than the inner ones. Catalogued counts on file run from 10 to 50 plates against a maximum of 61; a duty that seems to want the top of that range is often better served by a larger frame.

These models are catalogued alongside the B8T. Each has its own page with its dimensions, materials and part numbers.

SWEP B8DW - The most compact double-wall brazed plate heat exchanger in the SWEP range.

SWEP B8LAS - Compact AsyMatrix brazed plate heat exchanger pairing high thermal performance with low pressure drop.

SWEP BX8T - Compact All-Active brazed plate unit for heat pumps and container refrigeration, to 17.61 GPM.

SWEP E8AS - AsyMatrix brazed plate heat exchanger on the B8T frame, used mainly for heating tap water.

SWEP E8LAS - AsyMatrix brazed plate heat exchanger on the B8T frame for the highest thermal demands in tap water.

SWEP E8T - A compact copper-brazed plate heat exchanger for wall-hung, non-condensing boilers.