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Quotes - Engineering - SalesWhat we need from the old dryer
An old dryer's nameplate holds most of what is needed to replace it: a model number that usually encodes the flow, a rating, a pressure, a voltage and a connection size. The rest is what has changed in the plant since it was installed, which is the part a like-for-like order misses.
Start at the nameplate and write down everything on it. The model number identifies the series and, on nearly every line, the rated SCFM: an HPRN250 is 250 SCFM, an FLX4.5 is 450, a DXR 0125 is 125. The rating conditions matter as much as the number, because a dryer rated at 100 psig, 100°F inlet and 100°F ambient can be compared directly with the tables on this site, while one rated at a milder point needs adjusting. Then the maximum working pressure, the voltage and phase, the refrigerant, and the pipe size at the inlet and outlet.
Then look past the nameplate. The compressor may have been replaced with a larger one, the room may be hotter since a second machine went in, the plant may run a second shift it did not run when the dryer was bought. A replacement sized to the old nameplate carries the old plant's duty, not the current one. The three topic pages below take the nameplate, the cross-reference and the part-number lookup in turn.
- Model number and rated SCFM, with the rating conditions if the plate or manual gives them
- Maximum working pressure, voltage and phase, refrigerant, and inlet and outlet connection size
- Footprint and weight, and whether the unit is floor-standing, wall-mounted or receiver-mounted
- What has changed: compressor horsepower today, room temperature in summer, hours and shifts
- Whether the old dryer was ever short of capacity, which usually means going up a size rather than matching it
Copy these from the old unit before ordering.
- Model number, rated SCFM and the conditions behind that rating
- Inlet and outlet pipe size, voltage and phase, working pressure
- Today's compressor horsepower and the room temperature in summer
The replacement topics
Nameplate, cross-reference and part-number lookup
Replacing an Existing Dryer: How to read the old nameplate, which current series replaces the retired HPR, HPRN, FLEX, HITN and HPET Series, and what changes in connections, voltage and footprint when the new unit arrives.
Cross-Reference by Flow: A table of flow against the current series and model examples from 25 to 10,000 SCFM, and the method for crossing any other make by its rated SCFM at the standard point, including metric ratings.
Part Number Index: How this site organizes its series pages and part-number pages, how each series builds its model numbers, and where the four series cataloged on our sister site are found.
Like for like is rarely the right order
A dryer bought fifteen years ago was sized for the compressor and the room of fifteen years ago. If nothing has changed, the same rated SCFM in the successor series is the right replacement and the job is a nameplate read and a connection check. If anything has changed, and something usually has, the replacement is sized from scratch: delivered flow today, inlet temperature today, room temperature today, corrected with the sizing factors. The old dryer's rated flow is then one data point, and a useful one, because a plant that never had wet air on the old unit has just told you its minimum.
The retired series and their successors
Five series on this site are the previous generation. The HPR Series is replaced size for size by the HPRB Series, the FLEX Series by the FLXA Series under the same model numbering, the HITN Series by the HRHT Series, and the HPET Series by the HHPR Series. The HPRN Series, 75 to 1,200 SCFM, is covered by the non-cycling DXR Series at the same flows, or by the FLXA Series where the plant would benefit from cycling. The replacing page tabulates the pairs with what changes.
Connections, voltage and footprint
A successor is not always the same size or the same pipe. An HPRN250 was 2 in NPT; the DXR 0250 NA that replaces it is 1-1/2 in FNPT and needs two reducers. The 1,500 and 2,000 SCFM FLXA sizes moved from 4 in to 6 in flanges and grew in height. Small cabinet dryers went from 3/4 in NPT to 1/2 in FNPT. The current units are also lighter, use different refrigerants, and in several cases draw less power, none of which matters to the installation except the connections and the floor space, which we confirm on every replacement quote.
Crossing another make
A dryer from any other maker is crossed by its rated SCFM at 100 psig, 100°F inlet and 100°F ambient, once its rating point has been checked, because some are rated at a milder ambient or a metric reference point and read 15 to 20 percent higher than they would at ours. The cross-reference page puts the current series against flow from 25 to 10,000 SCFM. Send the old nameplate, or a photograph of it, to Sales and we return the match.
Before you swap out an old refrigerated dryer
On most lines the digits in the model are the flow, and a decimal usually stands for hundreds: a model ending in 250 is a 250 SCFM dryer, and a 4.5 on a cycling unit means 450. Write the figure down, then look for the rating conditions on the plate or in the manual. A unit rated at a milder point than 100 psig, 100°F inlet and 100°F ambient overstates what it really carried, and copying its number undersizes the successor.
Not always, so check before delivery day. Several current units have smaller connections than the dryers they succeed: the 250 SCFM non-cycling successor is 1-1/2 in FNPT where the old unit was 2 in, and needs a pair of reducers. The largest cycling sizes went the other way, from 4 in to 6 in flanges, and stand taller. Measure the floor space and the headroom under any overhead pipe along with the connection size.
Find it's rating point first. Some makes publish capacity at a milder ambient or a metric reference, and those figures read 15 to 20 percent above what the same dryer would carry at 100 psig, 100°F inlet and 100°F ambient. Take that margin off the rating, or correct it with the sizing factors, before reading across the flow table. A clear photograph of the plate is usually enough for us to make the conversion.
Treat the replacement as a fresh sizing. Take the delivered flow of every compressor that can now run at the same time, the summer room temperature with the new machine's heat in it, and the inlet temperature after the aftercooler, then apply the correction factors. The old dryer's rating still tells you something useful: if it never passed water on the original compressor, its figure is a floor for the new selection rather than a target.
Then the mounting decides part of the order. Note the style, footprint and weight, because the replacement has to fit the same position as well as the same flow. A wall-hung small cabinet needs its bracket kit and a bypass valve to suit; a receiver-mounted unit needs its inlet and outlet lined up with the tank connections. Setting a floor-standing dryer where a wall unit hung means new pipe runs and a new drain route that are cheaper to plan than to discover on the day.
