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Quotes - Engineering - SalesSSM, HMM and HMD: three membrane series
Two modular lines with the same bundles, plus an inline line
The SSM Series is a vertical modular dryer in nine sizes with helically wound bundles in epoxy-coated aluminum housings. A digital purge control synchronizes the sweep with demand, so a tool that sits idle half the shift does not waste sweep while it waits. The HMM Series uses the same nine sizes and the same flow table with a fixed sweep and no electrics; its housings are 3.5 to 5.5 in shorter and 3.2 to 4.8 lb lighter.
The HMD Series is the inline line: slim tubes from 2.5 in diameter that mount in any orientation, rated to 175 psig and 150°F. Sizes HMD20-1 to -6 run from 0.55 to 29.1 SCFM inlet at minus 40°F, and the -7, -8 and -9 assemblies parallel several -5 or -6 modules for more flow. RHD016SS, RHD026SS and RHD052SS versions in 304 stainless suit corrosive, hot or cold surroundings.
Both modular lines carry a 3-year warranty with the prefilter package fitted. The inline line carries 1 year as standard, extended to 3 years with its prefilter package.
How a membrane dries air
Water vapor leaves through the fiber wall
Compressed air runs down the bore of thousands of hollow fibers. Water vapor permeates the fiber wall faster than oxygen and nitrogen do, and a small stream of dried air, the sweep, carries it out of the shell to atmosphere. There is no liquid condensate to drain, no desiccant to regenerate and, on fixed-sweep units, nothing to wire.
Dew point
- +50°F down to -40°F
- Set by how much air you pass
- Inlet tables from 40 to 150°F
Pressure
- 200 psig, modular lines
- 175 psig, inline line
- Ratings published at 100 psig
Sweep control
- Fixed sweep, no electrics
- Demand-matched digital sweep
- Sweep equals inlet minus outlet
Housings
- Epoxy-coated aluminum, modular
- Nylon, CPVC and brass, small inline
- 304 stainless steel versions
Membrane models and their minus 40°F inlet flow
The flow shown is inlet air at minus 40°F pressure dew point, 100°F and 100 psig. The air delivered is less by the sweep: on the largest modular size, 46.2 SCFM in gives 27.4 SCFM out. Size on the outlet figure your tools need.
| MODEL | SERIES | SCFM IN AT -40°F | CONNECTION | H X W X D (IN) | WEIGHT (LB) |
| SSM1 | SSM Series | 0.53 | 3/8 in or 1/2 in | 16 x 4 | 8 |
| SSM2 | SSM Series | 1.88 | 3/8 in or 1/2 in | 20 x 4 | 9 |
| SSM3 | SSM Series | 3.5 | 3/8 in or 1/2 in | 24 x 4 | 10 |
| SSM4 | SSM Series | 5.87 | 3/8 in or 1/2 in | 32 x 4 | 11 |
| SSM5 | SSM Series | 7.9 | 3/4 in or 1 in | 25 x 5 | 14 |
| SSM6 | SSM Series | 17.1 | 3/4 in or 1 in | 32 x 5 | 17 |
| SSM7 | SSM Series | 18.5 | 1 in | 33 x 6 | 20 |
| SSM8 | SSM Series | 33.8 | 1 in | 38 x 8 | 40 |
| SSM9 | SSM Series | 46.2 | 1 in | 44 x 8 | 45 |
| HMM1 (size 1) | HMM Series | 0.53 | 3/8 in or 1/2 in | ||
| HMM2 (size 2) | HMM Series | 1.88 | 3/8 in or 1/2 in | ||
| HMM3 (size 3) | HMM Series | 3.5 | 3/8 in or 1/2 in | ||
| HMM4 (size 4) | HMM Series | 5.87 | 3/8 in or 1/2 in | ||
| HMM5 (size 5) | HMM Series | 7.9 | 3/4 in or 1 in | ||
| HMM6 (size 6) | HMM Series | 17.1 | 3/4 in or 1 in | ||
| HMM7 (size 7) | HMM Series | 18.5 | 1 in | ||
| HMM8 (size 8) | HMM Series | 33.8 | 1 in | ||
| HMM9 (size 9) | HMM Series | 46.2 | 1 in | ||
| HMD20-1 | HMD Series | 0.55 | |||
| HMD20-2 | HMD Series | 2.08 | 3/8 in NPT/BSP | 26.4 x 2.5 | 1.8 |
| HMD20-3 | HMD Series | 3.92 | 3/8 in NPT/BSP | 15.3 x 4.2 | 4.9 |
| HMD20-4 | HMD Series | 9.3 | 1/2 in NPT/BSP | 26.9 x 4.2 | 6.9 |
| HMD20-5 | HMD Series | 15 | 1/2 in NPT/BSP | 41 x 4.2 | 9.5 |
| HMD20-6 | HMD Series | 29.1 | 3/4 in NPT/BSP | 41.1 x 5.3 | 14.6 |
| HMD20-7 | HMD Series | 3 x HMD20-5 | 1 in NPT/BSP | 52 x 19.3 | 30 |
| HMD20-8 | HMD Series | 2 x HMD20-6 | 1 in NPT/BSP | 52 x 12 | 30.7 |
| HMD20-9 | HMD Series | 3 x HMD20-6 | 1 in NPT/BSP | 52 x 21.5 | 45 |
| RHD016SS | HMD Series | 16.3 at +50°F | 1/2 in NPT/BSP | 26.9 x 4.2 | 6.9 |
| RHD026SS | HMD Series | 27.6 at +50°F | 1/2 in NPT/BSP | 41 x 4.2 | 9.5 |
| RHD052SS | HMD Series | 55.2 at +50°F | 3/4 in NPT/BSP | 41.1 x 5.3 | 14.6 |
Dew point is a dial, not a fixed rating
A membrane trades flow for dryness. The largest modular size passes 138.1 SCFM in for 119.3 SCFM out at a plus 40°F dew point, but only 46.2 in and 27.4 out at minus 40°F. Decide the dew point the point of use really needs before choosing the size; plus 40°F suits indoor tools, while instrument air and lines that leave the building call for the lower setting.
The installation mistake we see most
Feeding a membrane oily or wet air. Liquid and oil aerosol blind the fibers, and unlike desiccant they can not be regenerated. The inline line ships with a Grade 5 filter as standard and recommends Grade 7 plus Grade 3 for contaminated systems; the modular lines take a filtration package and an optional filter monitor. Mount a coalescing filter right at the dryer inlet.
Where membranes win
Anywhere power is awkward, the flow is small and maintenance visits are rare: dental operatories, HVAC control panels, analyzer shelters, remote valve actuators and a single spray line. A membrane runs in any position, inside a cabinet or outdoors, with no drain to freeze.
Temperature and pressure
Hot inlet air carries more water and shrinks the flow a membrane can dry; the published tables run from 40 to 150°F inlet, so the derating can be read directly. Pressure works the other way, and the tables are built at 100 psig. Keep the dryer at the pressure it was sized for, upstream of any regulator.
Membranes in service
As long as the air reaching it stays clean, free of liquid and within its temperature limit; there is no wear part to replace on a schedule. What ends a module is contamination: oil aerosol or liquid water that slips past a neglected prefilter coats the fibers, and that loss of capacity is permanent. Years of running near the 150°F inlet limit are harder on the fibers than running cool. Record the outlet dew point at a known flow when the dryer is new; if the same flow later gives a wetter reading and the prefilter is in order, the module is the cause.
Usually because one of the conditions behind the table is not being met: 100 psig, the listed inlet temperature or the flow. A regulator ahead of the membrane, an inlet hotter than assumed or a tool drawing more than its data sheet says will each push the dew point up, and a sweep outlet restricted by a fitting does the same. Check those four before suspecting the module. Measure pressure right at the dryer inlet under load, not at the compressor, and read the inlet temperature on a summer afternoon, when a marginal selection shows itself.
Yes; it is the normal arrangement, and it lets a modest module hold minus 40°F reliably. The published flows assume saturated air at the listed inlet temperature, so air already dried to about a 38°F pressure dew point brings in far less water than the table allows for, and the outlet runs drier at the same flow. The refrigerated dryer also removes liquid that would foul the fibers. Keep the coalescing prefilter at the membrane anyway; the hybrid layout still carries oil aerosol and pipe scale between the two.
No; a membrane removes water vapor, and oil vapor and odor pass straight through it. Oil aerosol has to be stopped by the coalescing prefilter before it reaches the fibers, but vapor passes a coalescer too. Where a paint line, a food contact point or a lab instrument needs the vapor out, an activated carbon stage after the coalescer handles it, placed ahead of the membrane so the fibers see the cleanest air in the system. An oil-free compressor reduces the load on all of this but does not remove the need for the coalescer.
