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Quotes - Engineering - SalesThe HPD Series in practice
Thirteen models, one control strategy
The HPD Series covers 300 to 3,200 SCFM in 13 sizes, from the 98 in tall 300 SCFM unit on 1-1/2 in NPT to the 3,200 SCFM frame on 4 in flanges. Every size is rated for continuous duty, and each model is matched to a recommended coalescing prefilter and afterfilter so the package arrives sized as a set.
Read the dew point line carefully. As standard the dryer is set up to deliver minus 4°F, ISO class 3, which keeps water out of any line inside a heated building. In winter or low ambient it reaches minus 40°F on its own. Year-round minus 40°F needs the purge-boost option fitted with the energy management controller; order it at the start, because a class 2 specification will not be met in July without it.
Other options are a digital dew point monitor and a remote alarm contact, both worth having on a dryer whose outlet changes with the season.
Heat plus a smaller purge stream
Where an externally heated dryer sits between heatless and blower purge
An electric heater outside the towers warms the regeneration stream, and warm air carries far more water per cubic foot than cold air, so less of it has to be taken from the dried supply. This design amplifies the heated purge with ambient air and is rated at up to 15 percent less purge than a heatless dryer. An energy management controller reads temperature and humidity and adjusts regeneration to the load the dryer is really seeing.
Dew point
- -4°F, class 3, standard
- -40°F automatically in low ambient
- -40°F year-round with purge boost
Limits
- 150 psig maximum, 60 minimum
- Inlet 40 to 120°F
- Ambient 40 to 120°F
Electrical load
- Heaters 4.5 to 40 kW
- Full-load average 2.0 to 21.4 kW
- Rated for 100 percent duty
Hardware
- 1-1/2 in NPT to 4 in flanged
- 5 psi pressure drop
- 1,400 to 9,000 lb
Heated purge models, heater and average power
Each row lists the installed heater kW and the full-load average, which is roughly half the heater rating because the heater runs for only part of each regeneration. Size the electrical feed on the heater figure and the energy budget on the average.
| MODEL | SERIES | SCFM | CONNECTION | H X W X D (IN) | WEIGHT (LB) |
| HPD300 | HPD Series | 300 | 1-1/2 in NPT | 98 x 48 x 43 | 1,400 |
| HPD400 | HPD Series | 400 | 1-1/2 in NPT | 105 x 53 x 50 | 1,800 |
| HPD500 | HPD Series | 500 | 2 in NPT | 105 x 53 x 50 | 1,800 |
| HPD600 | HPD Series | 600 | 2 in NPT | 108 x 55 x 50 | 2,000 |
| HPD750 | HPD Series | 750 | 3 in flange | 114 x 60 x 62 | 2,400 |
| HPD900 | HPD Series | 900 | 3 in flange | 114 x 60 x 62 | 2,400 |
| HPD1050 | HPD Series | 1,050 | 3 in flange | 113 x 64 x 62 | 2,900 |
| HPD1300 | HPD Series | 1,300 | 3 in flange | 118 x 66 x 62 | 3,400 |
| HPD1500 | HPD Series | 1,500 | 3 in flange | 116 x 80 x 62 | 5,100 |
| HPD1800 | HPD Series | 1,800 | 3 in flange | 116 x 80 x 62 | 5,100 |
| HPD2200 | HPD Series | 2,200 | 4 in flange | 124 x 85 x 64 | 7,800 |
| HPD2600 | HPD Series | 2,600 | 4 in flange | 124 x 85 x 64 | 7,800 |
| HPD3200 | HPD Series | 3,200 | 4 in flange | 121 x 97 x 64 | 9,000 |
Heatless or heated?
At the bottom of this range a heatless dryer is simpler and cheaper to buy, and its purge is small in absolute terms. As flow climbs, every percent of purge becomes compressor horsepower. At 1,500 SCFM the heated design averages 10.0 kW at full load while trimming purge against heatless, and that is where the electric bill starts to beat the compressor bill. Compare both on the heatless page.
Inlet temperature matters twice
The inlet window is 40 to 120°F. Hot air carries more water into the beds, so a dryer fed straight from a compressor aftercooler on a summer afternoon works hardest just when its ambient regeneration air is also at its warmest. Put it in a ventilated room, not beside the compressors, and hold the inlet under 120°F with a properly sized aftercooler.
Filters ahead and behind
Every model has a published prefilter and afterfilter match. The prefilter is a coalescer that keeps compressor oil off the alumina; the afterfilter catches fines a heated bed sheds as it cycles. Skip either and you will be replacing desiccant or cleaning switching valves early. Details are on filter placement.
Where it fits
Plants with a large, steady demand for minus 4°F to minus 40°F air, spare electrical capacity, and so much compressed air already committed that they can not give up a heatless dryer's full purge. Typical sites are bottling and canning halls with outdoor runs, PET blow molding and central instrument air.
Planning around a heated purge dryer
The dryer keeps switching towers, but each regeneration leaves more water in the bed, and the dew point climbs over the following cycles rather than all at once. Because the standard outlet is minus 4°F and the dryer runs drier in cold weather anyway, a weak heater can go unnoticed for weeks in winter. Wire the remote alarm to a place someone watches, fit a dew point monitor on the outlet, and check the heater draws its rated current at each filter service so a failed element is found before the outlet gives it away.
Usually in floor space, not always in height, and never without a new electrical feed. At the small end the heated frames are much taller: the 300 SCFM unit stands 98 in at 1,400 lb, where the heatless frame covering that flow is 63 in at 1,215 lb. By 1,050 SCFM the two are both 113 in tall and within 25 lb of each other. Check headroom for desiccant filling, floor loading and port size. Then add what a heatless dryer never needed: a heater feed sized for the full rating, from 4.5 kW on the smallest model to 14 kW at 1,050 SCFM, and clearance around the heater housing.
Often yes, because several sizes share a frame, so the larger one takes no extra floor space. The 400 and 500 SCFM models are both 105 x 53 x 50 in at 1,800 lb, and the 750 and 900, 1,500 and 1,800, and 2,200 and 2,600 SCFM sizes pair up the same way. Moving up within a pair adds heater rating, from 6.0 to 7.0 kW at the small end, so confirm the feeder before ordering. Because the controller trims regeneration to the load it actually sees, the larger heater costs little extra while the plant is still running at today's flow.
It can, but on a single shift its advantage over a demand-controlled heatless dryer narrows. The heated design is rated for 100 percent duty and earns its keep by trimming purge hour after hour on a large, steady load. On one shift the compressors, and therefore the purge, are off for two-thirds of the day, so the air saved is smaller while the heater feed and the higher purchase price still have to be paid for. At the smaller end of the range, price both types for the actual hours before deciding.
