SWEP B439

By keeping it either warm, circulating or on glycol - never full of still water in an unheated space. Each channel holds 0.573 dm3, and a pack of 200 plates or more holds a lot of water that cannot be drained completely from a brazed unit. If it freezes, the plates split and the unit is finished.

Where the secondary side serves outdoor coils or a snow-melt loop, run that side on glycol and size the exchanger for the mix, because viscosity rises and the approach widens as concentration goes up. The common error is selecting on water and adding glycol at commissioning. Freeze Protection covers the control side.

Treat 155.5 m3/h (684.65 GPM) as a ceiling, not a design point. It is set by the ports - the flow at which port velocity and port pressure loss become the limit - and it says nothing about whether the plate pack can do your duty at an acceptable pressure drop.

A selection near the ceiling usually has most of its pressure drop in the ports, where it buys no heat transfer. If the duty needs that much flow on both sides at a modest pressure drop, the next step is a frame with larger ports, the B649 being the long-plate option above this one. If the flow is fine but the approach is not, more plates on the B439 is the answer instead.

For a replacement, the full designation off the nameplate is enough, or the SWEP article number. A photograph of the label beats a transcription, because the plate letter, the plate count and the connection suffix are exactly the fields that get miscopied.

For a new selection we need the duty: the fluid on each side including any glycol percentage, flow rate, inlet and outlet temperatures, the pressure drop each side can afford, and design pressure and temperature. Add the connection type the headers need and any approval the job specification names. With those, Request a Quote returns a specific B439 string, not a frame size.

B439 is the frame: the 979 x 304 mm plate. H is the plate type, the obtuse chevron with high heat transfer and high pressure drop. x200 is the plate count. /1P is a single pass on both sides.

SC is the material code - 316/316L stainless plates with copper braze. S is the pressure class, the 31 bar at 155 C category; the stamped figures on the unit are the actual rating.

4xDN100C says all four ports carry DN100 connections. The letters and bracketed number after it identify the connection style and variant, and they need to be matched as carefully as the rest, since two units identical up to the pressure class can still differ at the pipe joint.

It sets how much fluid the unit holds. Multiply 0.573 dm3 by the number of channels on a side - roughly half the plate count - and a large B439 carries a substantial volume on each circuit.

On a substation that hold-up is thermal lag, so the control loop needs tuning for a slower response. It also counts when dosing inhibitor or glycol, and it adds to the empty weight the published formula gives.

Each added plate adds surface and adds a parallel channel. More channels split the same flow more ways, so velocity and pressure drop fall, and the extra surface tightens the approach. Going from 200 to 400 plates is the difference between a unit that is short of surface and one that can hold a close approach at the same flow.

The costs are depth, weight and velocity. The published formula of 15.73 kg plus 0.89 kg per plate gives about 194 kg at 200 plates and about 372 kg at 400. Push the count too far for the flow and channel velocity gets low enough for fouling to settle. The frame tops out at 420 plates.