SMC AR30-03 Modular Pressure Regulator 3/8 Rc

A relieving regulator that sets machine air pressure

AR30-03 is the size 30, Rc 3/8 modular pressure regulator of the SMC AR series. Its job is to reduce the supply pressure to a stable set value and hold it as flow changes, protecting valves and cylinders from line fluctuations. The catalogue describes the construction as relieving type, meaning that when the set pressure is turned down, air on the outlet side vents through the regulator instead of staying trapped.

In the code AR30 is the series and body size, and 03 is the 3/8 port size. With nothing after 03 the regulator has the standard 0.05 to 0.85 MPa setting range, Rc thread, no bracket, no pressure gauge, and a flow from left to right. The how-to-order table adds letters for a bracket (B) or set nut (H), a gauge type (E square embedded, G round, M round with colour zone) and digital pressure switch options E1 to E4.

Technical specifications

Setting and reading the regulator

The set pressure range has a floor of 0.05 MPa and a ceiling of 0.85 MPa, so the supply to the regulator must be at least the set pressure plus the loss through the regulator, and not above the 1.0 MPa maximum. Note that the standard AR30 cannot dump residual outlet pressure when the inlet is exhausted; if that is required, the backflow-function version described below is the correct choice.

Adjustment is by knob; the catalogue tells you to unlock the knob before adjusting and to lock it afterwards. Always adjust by raising the pressure towards the setting rather than lowering from above, so the gauge shows the true regulated value, and fit a gauge or digital switch to confirm it.

Variants and companions in the AR family

The AR series has a backflow-function version (AR20K-D to AR60K-D in the current range) with a mechanism to exhaust the outlet air pressure reliably and quickly when the supply is cut off or when the pressure behind a cylinder differs from the front; this is a separate code and not part of AR30-03. In the current catalogue, AR30-03BG-D would describe the same regulator with a bracket and a round gauge supplied loose.

The regulator joins directly to AF filters and AL lubricators in a modular line, using the same port and body sizes, with spacers and brackets from the accessory list.

Documents and quotation

The SMC AR catalogue linked at the end of this page gives the order code table, specifications, options and dimensions for the current AR20-D to AR60-D range. Please confirm thread, gauge, bracket and set range before ordering. More air-preparation products are listed under Regulators. Seven Star LLC is an independent supplier and quotes the exact code on request.

AR30-03 and its current successor, AR30-03-D

AR30-03 is the code of the earlier generation of SMC modular regulators. SMC has superseded it with the -D series, and the current equivalent is AR30-03-D. The product photo and the official catalogue linked at the end of this page show the -D version. The body size (30), port (Rc 3/8), 0.05 to 0.85 MPa set range and relieving construction are carried over, so an AR30-03-D is the usual replacement for an AR30-03. The -D regulator has a push-to-lock knob: pull the knob to unlock it, and an orange mark appears in the gap; push it to lock, and the mark disappears. It also has new bracket, set nut and spare part numbers, so check accessories against the -D catalogue.

How the AR30-03 regulator works

Turning the knob compresses a pressure-regulating spring, which pushes down on a diaphragm. The diaphragm opens the main valve, and air flows from IN to OUT. The outlet pressure acts on the underside of the diaphragm. When it balances the spring force, the valve throttles back, so the outlet stays at the set value as flow demand changes. On the relieving type, turning the knob down, or a rise in outlet pressure above the setting, lifts the diaphragm off its relief seat, and the excess outlet air vents to atmosphere through the bonnet. The non-relieving version (semi-standard N) omits this venting path for systems where exhausting air at the regulator is not wanted.

The backflow-function model (AR30K-D) adds a check valve assembly. This lets outlet-side air flow back to the inlet when the supply is cut off, so residual pressure downstream can be released through the supply line. SMC states that the inlet pressure of the K type should be at least 0.05 MPa higher than the set pressure.

Selection & ordering guide for AR30-03-D

Options B, G, H and M are supplied loose and not assembled. With a gauge fitted, the standard type comes with a 1.0 MPa gauge (round gauge G36-10-01), and the 0.2 MPa type comes with a 0.4 MPa gauge. On the standard (non-K) model, if you order no gauge, or a G or M gauge, you cannot later convert it to the E, J or E1–E4 types. If you may want a square embedded gauge or a digital switch later, decide this at the time of ordering. Our team can help confirm the correct ordering code for your panel or FRL assembly.

Spare parts for the AR30-D

• Valve assembly: AR34P-060AS
• Diaphragm assembly: AR34P-150AS (relieving) or AR34P-150AS-N (non-relieving)
• Valve guide assembly: AR34P-050AS
• Square embedded gauge: GC3-10AS-D (standard range)

Installation & maintenance

• Set the AR30-03-D while watching both inlet and outlet pressure gauges. Turning the knob excessively can damage internal parts.
• Unlock the knob before adjusting and lock it afterwards. Otherwise the knob may be damaged and the outlet pressure may fluctuate. Operate the knob by hand only, never with tools.
• Release inlet and outlet pressure completely before replacing a gauge or changing its direction.
• Tighten gauges or fittings in the gauge port to 3 to 5 N·m while holding the regulator body.
• If the inlet pressure is lower than in the catalogue flow chart, the outlet pressure drop may be greater. Test with the actual equipment.
• Put an AF filter upstream, so that dirt does not reach the valve seat and cause creep or leakage.

Typical applications in Oman & the GCC

A regulator of this size sets the working pressure of individual machines and pneumatic panels. Examples include air cylinders on packaging and palletising lines, actuator supply in water treatment and desalination plants, test benches in oil and gas service workshops, and blow-off air in plastics and food plants. Plant air pressure often varies with compressor load, so an AR30-03-D gives each machine a steady pressure, which helps keep cylinder force and cycle time consistent. With the E1–E4 digital switch, the regulated pressure can also be monitored by a PLC.

Why source from Seven Star LLC

Seven Star LLC supplies SMC air preparation products across Oman and the GCC, including AR regulators, AF filters, AL lubricators and modular accessories. Send us the code on your existing AR30-03 and request a quote. Our team can help confirm the correct ordering code for the -D successor, including the gauge, set range and mounting options.