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Quotes - Engineering - SalesHigh Pressure Refrigerated Air Dryers, 500 to 725 psig
Dryers for PET blow molding boosters and high-pressure process air
A stretch-blow molding line runs its booster compressor at 500 to 600 psig, and the air that inflates the preform must be dry or the bottle walls carry water marks and the molds corrode. A plant-air dryer rated 200 psig cannot go there. The dryers on this page are built for 680 and 725 psig service, with stainless steel exchangers designed for the pressure, and sit downstream of the booster where the air is at its densest.
Two current series cover 45 to 2,410 SCFM. One is rated 680 psig in eleven sizes from 115 to 2,410 SCFM, threaded through 612 SCFM and on Class 300 flanges above, with an electronic controller and dew point display. The other is rated 725 psig in ten sizes from 45 to 1,000 SCFM with a stainless tube-in-tube exchanger, and publishes a capacity at 500 psig as well as at 725. The retired 725 psig series, 30 to 3,000 SCFM, is listed with its successor.
Air at 725 psig occupies about a sixth of the volume it fills at 100 psig, so the exchangers are compact for the SCFM they handle and the pressure drop across them is small. Every model delivers a 38 to 41°F pressure dew point at its rated pressure and 100°F inlet.
- 680 and 725 psig maximum working pressure; capacities published at 500 psig too
- 45 to 2,410 SCFM current, 30 to 3,000 SCFM including the retired series
- Stainless steel tube-in-tube or brazed-plate exchangers built for the pressure
- 1/2 in NPT to 4 in Class 300 flanges; 115 V single phase to 460 V three phase
Every 500 to 725 psig model
Thirty-five models with their rated capacity, connection and voltage; a high-pressure dryer is selected on SCFM at the line pressure, so confirm which pressure the capacity is quoted at. Current series first, the retired series and its replacement after.
| PART NUMBER | SERIES | SCFM | CONNECTION | VOLTAGE | STATUS |
| APET-45 | APET Series | 45 | 1/2 in NPT | 115/1/60 | Current |
| APET-65 | APET Series | 65 | 1/2 in NPT | 115/1/60 | Current |
| APET-80 | APET Series | 80 | 1/2 in NPT | 115/1/60 | Current |
| APET-125 | APET Series | 125 | 1/2 in NPT | 115/1/60 | Current |
| APET-200 | APET Series | 200 | 1 in NPT | 115/1/60 | Current |
| APET-260 | APET Series | 260 | 1 in NPT | 230/1/60 | Current |
| APET-415 | APET Series | 415 | 1 in NPT | 460/3/60 | Current |
| APET-570 | APET Series | 570 | 1 in NPT | 460/3/60 | Current |
| APET-860 | APET Series | 860 | 1 in NPT | 460/3/60 | Current |
| APET-1000 | APET Series | 1,000 | 1 in NPT | 460/3/60 | Current |
| HHPR-115 | HHPR Series | 115 | — | 115/1/60 | Current |
| HHPR-150 | HHPR Series | 150 | — | 115/1/60 | Current |
| HHPR-200 | HHPR Series | 200 | — | 115/1/60 | Current |
| HHPR-300 | HHPR Series | 371 | 1-1/2 in MNPT | 460/3/60 | Current |
| HHPR-600 | HHPR Series | 612 | 2 in MNPT | 460/3/60 | Current |
| HHPR-750 | HHPR Series | 768 | 3 in Class 300 RF flange | 460/3/60 | Current |
| HHPR-1000 | HHPR Series | 1,000 | 3 in Class 300 RF flange | 460/3/60 | Current |
| HHPR-1200 | HHPR Series | 1,237 | 3 in Class 300 RF flange | 460/3/60 | Current |
| HHPR-1600 | HHPR Series | 1,610 | 4 in Class 300 RF flange | 460/3/60 | Current |
| HHPR-2000 | HHPR Series | 2,000 | 4 in Class 300 RF flange | 460/3/60 | Current |
| HHPR-2400 | HHPR Series | 2,410 | 4 in Class 300 RF flange | 460/3/60 | Current |
| HPET-0.17 | HPET Series | 30 | 1/2 in NPT | 115/1/60 | Replaced by HHPR |
| HPET-0.2 | HPET Series | 45 | 1/2 in NPT | 115/1/60 | Replaced by HHPR |
| HPET-0.25 | HPET Series | 65 | 1/2 in NPT | 115/1/60 | Replaced by HHPR |
| HPET-0.33 | HPET Series | 95 | 1/2 in NPT | 115/1/60 | Replaced by HHPR |
| HPET-0.5 | HPET Series | 165 | 1-1/2 in NPT | 115/1/60 or 208-230/1/60 | Replaced by HHPR |
| HPET-0.75 | HPET Series | 200 | 1-1/2 in NPT | 115/1/60 or 208-230/1/60 | Replaced by HHPR |
| HPET-1.0 | HPET Series | 300 | 1-1/2 in NPT | 460/3/60 | Replaced by HHPR |
| HPET-1.5 | HPET Series | 500 | 1-1/2 in NPT | 460/3/60 | Replaced by HHPR |
| HPET-2.5 | HPET Series | 750 | 1-1/2 in NPT | 460/3/60 | Replaced by HHPR |
| HPET-3.5 | HPET Series | 1,000 | 1-1/2 in NPT | 460/3/60 | Replaced by HHPR |
| HPET-4 | HPET Series | 1,250 | 3 in NPT | 460/3/60 | Replaced by HHPR |
| HPET-6 | HPET Series | 1,750 | 3 in NPT | 460/3/60 | Replaced by HHPR |
| HPET-7.5 | HPET Series | 2,000 | 3 in NPT | 460/3/60 | Replaced by HHPR |
| HPET-10 | HPET Series | 3,000 | 3 in NPT | 460/3/60 | Replaced by HHPR |
Three series for high-pressure air
Sizing at 40 to 50 bar
A PET line is sized from the booster's delivery in SCFM and its discharge pressure. A booster delivering 300 SCFM at 580 psig takes the 371 SCFM model of the 680 psig line or the 415 SCFM model of the 725 psig line; the capacity published at 500 psig is the safer figure for a booster that runs at 500 to 550 psig, because capacity falls with pressure. Add the usual derates for inlet temperature: a booster aftercooler that discharges at 110°F costs 20 percent of the rating, and boosters on a hot mold-shop mezzanine often do.
Where the dryer goes in a PET system
The usual layout is a low-pressure compressor and dryer feeding the booster, then the high-pressure dryer after the booster's aftercooler and receiver, then the high-pressure filters and the blow molder. Drying only at low pressure is not enough: the booster compresses the air five times further, the water that was vapor at 100 psig condenses at 580 psig, and it arrives at the mold as liquid. The high-pressure dryer takes that condensate out at the pressure where it forms.
What is in the machine
The 680 psig line pairs a hermetic refrigeration circuit with pressure-rated exchangers, a solenoid drain on the 115 to 200 SCFM sizes and a timed electric drain from 300 SCFM up, and an electronic controller that shows dew point; it is air-cooled throughout and built to UL standards. The 725 psig line uses a corrosion-resistant stainless tube-in-tube exchanger with better than 98 percent moisture separation, an initial pressure drop of about 5 psi, and NEMA 1 electricals in 115 V, 230 V and 460 V builds by size. The retired series used 316 stainless brazed-plate exchangers and a filter-separator with a timed drain; its model numbers are the refrigeration compressor horsepower.
Beyond PET
The same dryers serve any line running between 200 and 725 psig: pneumatic presses and clamps at 250 psig, test benches, high-pressure blow-off and cleaning, and engine starting-air systems. Filters, drains and bypass valves must carry the same pressure rating as the dryer; the drains page lists timed drains to 6,000 psig and the PET blow molding page covers the complete air system. Pressures above 725 psig move to the ultra-high-pressure dryers.
Sizing a dryer behind a PET booster
About 20 percent of the rating, and it changes the selection. A 300 SCFM booster at 580 psig fits the 371 SCFM model of the 680 psig line on paper, but derated by a fifth that model is short. The next size, 612 SCFM, covers it with room to spare. The 415 SCFM model of the 725 psig line clears it only if its capacity at 580 psig, not at 725, survives the derate. Check the aftercooler discharge on a summer afternoon.
Yes, every component on the high-pressure side. A plant-air filter housing borrowed from the low-pressure side and fitted at 580 psig is a bowl waiting to fail, and the same goes for drains and bypass valves. Rate each item to the booster's relief setting rather than its running pressure. The drains page carries timed drains well above 725 psig, so there is no reason to compromise on that part.
Because the booster puts the water back in liquid form. Air dried to a 38°F dew point at 100 psig is far from dry once it is compressed to 580 psig, and the vapor condenses in the booster's receiver and the lines to the blow molder. The first sign is often water at the booster receiver drain; the next is marks in the bottle wall and rust in the molds. A dryer after the booster cures it.
An initial drop of about 5 psi, which on a 580 psig booster line is under 1 percent of the pressure and costs very little. Dense air moves slowly through the exchanger, so the figure stays low as long as the tubes stay clean. A drop that keeps rising points to oil and carbon carried from the booster's cylinders, which a high-pressure coalescing filter ahead of the dryer would have stopped.
The three smallest sizes, 115 to 200 SCFM, use a solenoid drain; from 300 SCFM up it is a timed electric drain. At these pressures each opening vents dense, expensive air, so set the open time to the shortest that clears the condensate and lengthen the interval in dry weather. Keep a strainer ahead of the solenoid, because scale from a new high-pressure receiver will hold the valve open and the drain will vent continuously.
