Sondex & Danfoss PHE Gaskets: Replacement Guide
Sondex & Danfoss PHE Gaskets: A Practical Replacement Guide
Danfoss bought Sondex in 2016. Both names are still in use. A search for sondex plate heat exchanger gaskets often ends with a photo of a tag marked XG. The two ranges run on different plate patterns, so the gasket has to match the unit, not the name on the purchase order.
Which Range Do You Have?
SONDEX gasketed units carry the S prefix, from the small S4 up to S251. Units marked XB, SL, SLS or SW are brazed or welded and take no gaskets at all. Danfoss's own gasketed range is XG, with sizes from XG10 to XG95.
How to Identify a Sondex Plate Heat Exchanger
The tag string has five parts. In S43-IS16-21-TKTL89, 43 is the plate type, IS is the frame, 16 is the design pressure in bar, 21 is the plate count, and TKTL89 is the plate grouping. Frame letters run IS, IG, FS, FG and ST. One square-on photo of the tag removes most of the back and forth.
Gasket Attachment Types
Sondex plates use four attachment styles: glued, Sonder Snap, SonderLock and hang-on. A sondex sonderlock gasket sits in the groove and is held by its own profile, so no adhesive is needed. Hang-on gaskets hook over the plate edge and lift off in one piece. Glued gaskets must be scraped out of the groove before the new one goes in. The styles do not interchange on the same plate. A photo of the plate edge shows tabs, a hooked edge or a bare groove.
Danfoss XG: Clip-On, With One Exception
Most danfoss xg gasket sets are clip-on. The XG10 is the exception and takes a glued gasket. XG plates come in L and H patterns, where H gives more heat transfer and a higher pressure drop. A gasket set for an L plate will not fit an H plate of the same nominal size.
Common Sizes: S37 and S39
S37 and S39 sit in the middle of the range and appear often in replacement requests. They share a family name but not a plate size, so a sondex s37 gasket will not stretch to fit an S39. The model alone is not enough. Plate count and A-measurement go on the order as well.
What to Send
Five items cover most checks: a nameplate photo, a plate edge photo, the plate count, the medium with its operating temperature, and the A-measurement if the unit is open. With those, the reply is a check against a known pattern instead of a guess.
Questions on a Sondex or Danfoss unit? Send the tag and plate photos to info@newroc-phe.com.
FAQ
Q: My tag says S14A. Which gasket do I need?
A: Hang-on. The letter A means hang-on, while S14 without the A is SonderLock.
Q: Is there a Danfoss to Sondex cross-reference table?
A: No official one. Match the plate dimensions, plate count and gasket style, and the unit can be confirmed either way.
