Health & Safety

ISO 45001


ISO 14001

+44 (0) 1424 205140

12457 Dehydrator

The DRALLIM Waveguide Dehydrator type 12457 is an energy saving integrated unit of compact dimensions designed specifically to supply low pressure dry air to waveguides and aerial feeders. The unit is free standing and can be sited in any convenient location. Its low noise level of around 60dBA is quiet enough to allow it to be sited in manned areas.

The dehydrator utilises a well proven heatless reactivation system capable of supplying dry air at a dewpoint of better than -40deg C via either five or ten outlets to which 6mm OD tubing can be connected (Adaptors are available if this size does not suit user requirements); push-fit bulkhead couplings are sited at the top rear of the cabinet. Air is supplied through these at low pressure, reduced by the output regulator to between 0.5
and 7psi. Initial alarm and safety valve settings are selected in accordance with a nominal supply pressure of 2psi.

Two versions are available, designated 12457/L5 and 12457/L10, both of which operate from a voltage of 230V AC 50Hz. Each delivers in excess of 35 ft3 /hr.


Uses twin tower molecular sieve, adsorption system.


Environmental Considerations


230V A.C. 50Hz single phase. 


2 metre mains lead and plug supplied 

(gland at top of equipment). 

Current consumption:

-5.9A upon start-up only 

-1.8A running current. 

Rating plate affixed to equipment. 


Ambient operating temp. 0 to 38°C (32-100°F).  


443mm wide x 1060mm high x 330mm deep.  


Floor standing.  



Noise Level

typically 60dBA maximum at 1 metre, all planes. 

Operational Features


1/3HP rocking single cylinder piston compressor  7 bar(100psi max). 

Stop/start pressure 32 – 65 psi. 

Minimal transmission of vibration, compressor 

fitted via rubber mounts. 

Intake filter fitted with replaceable element.  

Safety Relief

fitted to compressor to protect dehydrator  


against overpressure (125psi) and downstream of regulator to protect aerial feeder (5psi). 

 Air Drier

Twin bed heatless pressure – reactivated 

adsorption type. Each bed on line 1 

min/regenerating 1 min.  

Automatic changeover by electro-mechanical 

process timer with memory. 

Desiccant, grade 4A molecular sieve, 3-5mm. 

Inlet and outlet filtration by sintered 35 micron bronze filters at each drier bed port. 

Output dewpoint detection circuit with  

associated indication and test facilities.  


Output dewpoint detection circuit with associated Detection indication and test facilities. 

Automatic bypass to atmosphere of any 

 insufficiently dried air. Set to operate at 

-20ºC/reset at -25ºC. 

“Brown” colour coded humidity sensing element.  

Fail safe operation. 

 Dry Air Storage

Internal welded steel air storage reservoir       

Provides a 12.5 litre reserve of dry air. 

Safety relief valve set at 102psi with integral ring pull. 

Fitted with ¼ turn drain ball valve. 

Backup Functionality  


Can be used as a “main” unit operating in conjunction with a “standby” unit easily converted from an existing 12437 or 12447. 

Functionality is automatic and distribution from both units to feeders remains independent. 

 Increases output in high demand situations. 

Provides a failure facility whereby if the “main” fails, the “standby” dehydrator supplies dry air to both air storage reservoirs and hence feeders connected to both units. 

 Quick connect self-sealing sockets are fitted to both units. 

One simple 6mm OD flexible tube links the “main” and “standby” units. 

Non-return valves prevent role reversal. 

Dry Air Output


0.5 – 7.0 psi controlled by front panel mounted tamperproof (relieving type) regulator. 


35 ft³/hr (16.5 litres/min) at any set output pressure. 


Better than -40ºC. 


5 or 10 male output bulkhead couplings, intended for 6mm OD flexible hose, situated at the top of the equipment. Each protected by an individual non-return valve to prevent cross-feeding and leakage. 

Alarm Indication


Multi-chip LEDs with current limiting resistors. 

Receiver Filling/Dry (Green) 

Receiver Not Filling/Wet (Red) 

ie output being bypassed to atmosphere. 

Running command (Amber) neon 

ie compressor should be active. 

Low Output pressure (Red neon) adjustable, factory set at approx.  1.0 psi. 

High Output pressure (Red neon) adjustable, factory set at approx. 3.5 psi. 

High Output Flow (Red) adjustable throughout range of individual output flowmeters 

5 or 10 fitted dependent upon number of outlets.  


15 Way “D” type connector provided (at top of equipment) to enable remote indication of alarms; individual (non-commoned) clean contacts rated at 5A being provided as both normally open and normally closed volt free contacts provided for each of:  

    1. Mains Fail 
    2. High Humidity (vessel/w.guide not filling) 
    3. Low Output Pressure 
    4. High Output Pressure 
    5. High Output Flow

37 way “D” type connector fitted to provide individual low output (waveguide) pressure alarms both normally open and normally closed (non-commoned) for each flow tube. Each switch is fitted to a tee between the non-return valve and output bulkhead coupling. The switches are adjustable throughout the range 0.4 – 1.0psi, factory set just below 1.0psi 



Combined on/off switch/lamp and circuit breaker incorporating thermal protection rated at 10A. 

Total running hour meter to indicate compressor  

usage, permanent LCD display. 

LOW output pressure alarm lamp. 

HIGH output pressure alarm lamp. 

Receiver FILLING lamp. 

Receiver NOT FILLING lamp. 

High Output Flow lamps (one per outlet). 

RUNNING COMMAND lamp indicating when 

compressor should be running. 


63mm dia. “Compressor” pressure gauge 0-150psi (liquid filled). 

63mm dia. “Receiver” pressure gauge 0-160psi. 

63mm dia. “Output” pressure gauge 0-15 psi. 

Individual flow indicators 0-350 litres/hour (5 or 10) with “toggle” type stop valves to display instantly whether in the open or closed position. 

Tamperproof precision output regulator to adjust output pressure 0.5 – 7.0psi (accurate within 10mbar over operational range of equipment). 

Non-return valve fitted to each output to prevent cross-feeding. 

Test Facilities

 Element Check

A momentary pushbutton switch introduces un-dried compressor air to the sensing element to check operation of the humidity sensor.  

Circuit Check

“Wet” and “Dry” circuit check pushbuttons to  

electrically test humidity detector circuitry. 

Tester Humidity Detector 1A compatible via test jack sockets located internally.  


Momentary pushbutton enabling the compressor to run continuously so that, for example, tests may be carried out on the humidity detector without waiting for receiver pressure to drop.  

Additional information

Operating voltage

230V A.C. 50Hz

Output pressure

0.5 – 7 psi

Dry air dewpoint


Product Enquiry

Please contact our sales for the product information. E-mail : [email protected]