At a glance
- Type
- Membrane dryer
- Job
- Point-of-use moisture removal
- Select by
- Delivered flow, pressure and required dryness
- Not the same as
- ChillDry refrigerated / DryTech desiccant
Overview
MembraDry MD is the membrane air-dryer range. It dries compressed air by selective permeation of water vapour through the walls of a hollow-fibre polymer bundle: no moving part, no electrical load at the drying stage, no desiccant bed, and no condensate to drain at the dryer itself. It is the third drying route SIND offers, alongside refrigerated (ChillDry CD) and desiccant (DryTech DT) drying, and the only one designed for point-of-use installation rather than the compressor room.
Model range
MembraDry MD covers point-of-use duties. Modules are combined in parallel banks to reach the required delivered flow.
What it does
Membrane drying
- Method
- Hollow-fibre permeation, counter-current sweep
- Power
- None at the drying stage
- Not for
- Large central plant flow
Where it fits
Point of use
- Typical use
- Instrument, analyser, laser-assist or cabinet branch
- Sites
- Remote, mobile, cold-climate, offshore
- Must have
- Coalescing and particulate filtration upstream
How to choose
By flow and dryness
- Start with
- Delivered flow at the point of use
- Then check
- Inlet pressure, inlet temperature, sweep allowance
- Before a quote
- Confirm model, sweep ratio and connections
Technology
Technology Platform Principle
MembraDry MD dries compressed air by selective permeation of water vapour through the walls of a hollow-fibre polymer bundle.
Key Selection Points
Performance Boundaries
The dryness a membrane dryer achieves depends on inlet pressure, inlet temperature, flow and sweep, and is properly quoted as suppression below inlet saturation rather than an absolute dew point.
More technical detail
Technology Platform Principle
A membrane module has a small flow ceiling per unit and continuously discards part of its own dried product as sweep air, so on a plant header at large flow it is uneconomic. On a branch, in a cabinet, on a skid or in a vehicle it is often the cheapest way to get dry air where it is used: no cable, no drain and no service visit attaches to the drying step. The range sits downstream of the main treatment train, or in place of it where the duty is small and dispersed.
Key Selection Points
- Hollow-fibre membrane drying with counter-current sweep: no moving part, no electricity at the drying stage, no desiccant, no condensate to drain at the dryer.
- Point-of-use installation; compact envelope and low mass suit wall, skid, cabinet and vehicle mounting.
- Unaffected by vibration, tilt and intermittent duty: no bed to fluidise, no valve to cycle, no liquid level to hold.
- Removes water vapour only; oil aerosol, particulate and odour pass through or damage the bundle, so upstream filtration is mandatory.
- Continuous drying, no regeneration switch: no cyclic dew-point excursion, no changeover noise pulse.
- 50 Hz standard. 60 Hz configuration on request.
Performance Boundaries
The upstream air quality sets the service life of the bundle. Oil aerosol and particulate destroy or block the hollow fibres, and the dryer cannot remove them: coalescing and particulate filtration, with bulk separation and a working drain ahead of them, is mandatory rather than optional.
Selection Logic
- Work from the delivered flow at the point of use, not compressor nameplate flow.
- Establish the branch flow, actual inlet pressure, and inlet temperature after the aftercooler.
- Express the dryness needed as suppression below inlet saturation.
- Allow for the sweep, which comes out of the delivered flow.
Selection & quote checklist
- Set delivered flow
- Read pressure and temperature
- State the suppression
- Lock the model
Applications
Case A: Remote Valve Station and Telemetry Hut
An instrument and control air branch sits far from the compressor room and has no convenient power or drain.
Case B: Cold-Climate or Outdoor Pipework
An outdoor branch is exposed to freezing conditions.
Case C: Vehicle, Skid or Marine Package
Rail and heavy-vehicle braking and control air, and marine and offshore skid packages, need dry air on a moving platform.
Ownership & service
Energy, maintenance and service
Total Cost of Ownership
The drying stage has no electrical load and no refrigerant, so there is no power bill and no refrigerant servicing attached to it. The operating cost is the sweep: a continuous fraction of the dried product is discarded to carry the permeated vapour away, and that sweep is compressed air already paid for.
At large continuous flow the module ceiling and the sweep make the membrane route uneconomic against a refrigerated or desiccant dryer. On a branch, in a cabinet, on a skid or in a vehicle, where the alternative is a cable, a drain and a service visit, it is often the cheapest way to get dry air where it is used.
With no moving part and no bed to regenerate, mechanical wear and cycle losses are minimal. The replaceable items are the upstream filter elements and drains, and the module itself, which is replaced as a unit.
Maintenance Cost Structure
Specific intervals are per the random manual; the table above is category-general reference.
| Item | Typical interval | Notes |
|---|---|---|
| Upstream filter elements | Per pressure drop | Protects the bundle from oil aerosol and particulate. |
| Separator and filter-bowl drains | Monthly check | A blocked drain lets condensate reach the bundle. |
| Membrane module | Not field-serviceable | Replaced as a unit; life depends on upstream air quality. |
Service Support
SIND provides remote technical support (working-day response), spare parts supply by full SIND model number, and commissioning guidance. Specific service terms vary by region — confirm with the local authorised service provider or SIND commercial representative.
Reference data
Full specification and reference tables
| Application | Why membrane |
|---|---|
| Instrument and control air at remote valve stations and telemetry huts | No cable, no drain, no service visit at the drying step |
| Outdoor and cold-climate pipework branches | Continuous drying; no liquid level to freeze at the dryer |
| Food, beverage and pharmaceutical point-of-use drying | Water vapour removed at the point of use |
| Electronics and precision-manufacturing cabinet air | Compact envelope suits cabinet mounting |
| Laser cutting assist air | Local branch drying without re-drying the plant |
| Pneumatic conveying of hygroscopic product | Drier conveying air on the branch |
| Marine and offshore skid packages | Unaffected by vibration and tilt |
| Rail and heavy-vehicle braking and control air | Dries on a moving platform, no moving part |
| Mining and underground instrumentation | No electrical load at the drying stage |
