Plate and Brazing Materials

Yes. SC puts 316/316L plates where NC has AISI 304, with the same copper braze, so it is a step up in corrosion resistance and changes nothing about how the unit pipes in.

The substitutions to refuse run the other way. Do not replace SC with NC unless the water is known to be benign, and never replace a copper-free SN or SPS unit with a copper-brazed one: the original code was chosen because of what is in the fluid. If the old unit failed by corrosion, a like-for-like replacement repeats the failure, so tell us what it was running on.

Pinhole leaks from one circuit into the other, appearing after a period of normal service. The usual first sign is a closed loop that keeps gaining or losing fluid with no visible leak anywhere.

It is routinely taken for a manufacturing defect, and the unit is replaced with an identical one that fails the same way. Pool and spa heaters are the classic case, along with chlorinated or brackish cooling water. The fix is SMO 254 plates, the MC code. Pool and Spa Heating covers that duty.

No. This is the selection error to watch for, because SMO 254 sounds like the premium answer to everything. The MC code is SMO 254 plates with copper braze. It resists chlorides at the plate and leaves the copper filler exactly as exposed as it is in an SC unit.

Plate and braze are seperate decisions. Choose the plate for corrosion by the fluid, and the braze for chemical attack and temperature. Ammonia and deionized water are braze problems, so they are answered by SN or SPS.

Mainly choice of frame. Copper brazing is the standard build across the range, while nickel-brazed and All-Stainless constructions are offered on particular frames, the SWEP B8T and B16 among them.

The pressure and temperature rating of a copper-free build is also its own and should not be assumed from the copper-brazed version of the same frame - call for rating. In practice the material requirement narrows the list of frames first, and the duty then picks from what remains.

Only if the rest of the loop is copper-free as well. An SPS exchanger removes one source of copper; copper tube, brass valves and bronze pump parts elsewhere in a deionized loop keep supplying it.

The same reasoning applies on ammonia, where any copper alloy in the circuit is attacked. Walk the whole wetted path before blaming the exchanger for a conductivity reading, and when ordering, state that the duty is deionized water so nothing copper-bearing is supplied by default.