Refrigerated Air Dryer Omega Air RDT 75 — 75 m³/h, Pressure Dew Point +3 °C, 16 bar

Why a Compressed Air Dryer Is Needed

Atmospheric air contains water vapour. When compressed, vapour concentration multiplies — and on cooling after the compressor it condenses into liquid water. Water in a pneumatic system means:

• Corrosion inside pipework, receivers, valves and cylinders
• Product damage when compressed air contacts the workpiece directly (painting, food production)
• Automation failures — solenoid valves, pressure sensors and pneumatic logic elements fail from corrosion and ice formation
• Winter failures — water freezes in pipelines routed through unheated spaces
• Unstable lubrication in lubricated systems: water washes lubricant from cylinders and tools

A refrigerated dryer cools compressed air to +3 °C, at which point most water vapour condenses and is removed through the condensate drain. The outlet delivers dry air with a guaranteed pressure dew point of +3 °C.

How the RDT 75 Works: Three-Stage Heat Exchanger

The key design feature of the RDT series is a three-stage «3-in-1» aluminium channel heat exchanger:

1. «Hot air — cold air» stage (recuperator): incoming hot air is pre-cooled by the dry outgoing air. This reduces the load on the refrigeration circuit and prevents condensation on the outlet pipework.
2. «Air — refrigerant» stage (evaporator): air is cooled to +3 °C. At this temperature water vapour condenses into droplets.
3. «Air — air» stage (re-heater): the dry cold air is warmed by the incoming flow, leaving at a temperature close to the inlet temperature. The pipework after the dryer remains dry.

Technical Specifications — RDT 75

⚠️ Important — correction factors: the 75 m³/h flow is specified at ISO 7183 standard conditions: inlet +35 °C, pressure 7 bar, ambient +25 °C. Under different conditions actual capacity decreases. For example, at 5 bar and ambient +40 °C the actual flow the RDT 75 can dry to a +3 °C dew point falls to approximately 50 m³/h. Account for this when designing the system.

RDT Series: Full Range

What the Catalogues Don’t Tell You: 3 Critical Points

1. Correction factors are mandatory

The catalogue figure of 75 m³/h is at ideal conditions. In real production, system pressure is often 5–6 bar and summer workshop temperatures reach +35…+40 °C. Under these conditions actual capacity falls 30–50%. Before purchasing, ask the Acvatron SRL engineer for the correction factor table for your specific conditions.

2. The 3 µm pre-filter is not optional

The standard RDT 75 configuration does not include an inlet filter. Without a 3 µm pre-filter, oil aerosol from the compressor blocks the aluminium channels of the 3-in-1 heat exchanger. Heat transfer efficiency drops, the dew point rises above +3 °C and the dryer effectively stops working. The pre-filter protects the investment and guarantees stable air quality.

3. Mounting location: not under the ceiling

The RDT 75 has M8 bolt mounting points for wall installation. But if mounted too high under the ceiling — where the hottest air accumulates — the dryer will trip on alarm «Cln» (High condensation temperature). Optimal installation height: no higher than 2 m from the floor, in an area with adequate ventilation.

MODBUS — Why It Matters

The RDT 75 supports the MODBUS protocol for remote monitoring. In 80% of cases a dryer failure is preceded by a gradual rise in refrigerant temperature that can be tracked remotely, allowing the cause to be addressed before the dew point starts to drift. MODBUS allows the dryer to be integrated into the facility’s monitoring system with advance warning alerts.

Installation and Start-Up Rules

1. Install the 3 µm pre-filter at the dryer inlet — mandatory.
2. Ensure adequate ventilation around the dryer: minimum 500 mm clearance on sides and 1000 mm above.
3. Install a bypass line with ball valves — for dryer maintenance without stopping production.
4. Check the condensate drain before start-up: it must open when filling and close when empty.
5. Do not mount under the ceiling in spaces without forced ventilation.

Expert Opinion

“If you are choosing the RDT 75 or RDT 100, pay close attention to the MODBUS protocol, because in 80% of cases critical refrigerant temperatures are missed — temperatures that can be monitored remotely to prevent compressor failure. Omega Air is not ‘something from China’: it is Slovenian manufacturing with genuine material quality. The 3-in-1 aluminium heat exchanger is one of the best solutions in this class. But RDT is not a ‘fit-and-forget’ dryer: without a pre-filter and correct installation you will quickly end up with a blocked heat exchanger and degraded dew point.”

Vitali Bolucevschi, Chief Engineer at Acvatron SRL, 15 years in the industry

Which Compressors Is the RDT 75 Suitable For

Why Acvatron SRL

Official Omega Air Distributor in Moldova

Acvatron SRL supplies Omega Air RDT series dryers with the full manufacturer’s document package, CE certificates and warranty.

Engineering Selection with Correction Factors

Not sure whether you need the RDT 75 or RDT 100? Provide your compressor output, working pressure and ambient temperature — the Acvatron SRL engineer calculates the correct model with correction factors applied.

Complete Solution

Acvatron SRL supplies the dryer together with the required filters (3 µm pre-filter, post-filter), condensate drains and bypass kits. Everything for a correct installation from one source.

Documents for Legal Entities

Invoice and contract. Warranty and post-warranty service in Chișinău.

FAQ

❓ Why can actual flow differ from the catalogue figure of 75 m³/h?

The catalogue figure is at ISO 7183 standard conditions: inlet +35 °C, 7 bar, ambient +25 °C. With deviations, correction factors apply. At 5 bar and +40 °C ambient, actual flow falls to approximately 50 m³/h. Calculate using your actual conditions before selecting the model.

❓ Is a dryer needed if the compressor already has a water separator?

A water separator removes only liquid droplets that have already condensed. A refrigerated dryer removes moisture in vapour form by cooling air to the +3 °C dew point. They are different devices — a water separator does not replace a dryer; it only reduces the load on it.

❓ What does alarm code «Cln» mean?

High condensation temperature — the condenser has overheated. Causes: inadequate ventilation, blocked condenser (dust on aluminium fins), high ambient temperature. Clean the condenser with compressed air and ensure adequate ventilation clearances.

❓ What refrigerant is used in the RDT 75?

HFC — R134a or R407C depending on the version. The circuit is hermetically sealed; refrigerant recharging is not required under normal operation.