Delta-Elektrogas RAG Air/Gas ratio regulators

The RAG type regulator has the scope of maintaining a constant air-gas ratio upstream of gasburners on installation without preheated air. It is equipped with a by-pass adjustable on site
and can be used as zero-pressure regulator.




In 1961 Elettromeccanica DELTA s.p.a. was founded in Arcade (TV) with the aim of designing and manufacturing oil burners with mechanical atomization. Today, Elettromeccanica DELTA and its brand Deltapumps and Elektrogas are leading manufacturers of gear oil pumps and safety control valves, exported in more than 60 countries in the world.


The RAG type regulator has the scope of maintaining a constant air-gas ratio upstream of gasburners on installation without preheated air. It is equipped with a by-pass adjustable on site
and can be used as zero-pressure regulator.


The regulators are made of aluminum alloy die-cast, with a range for inlet/outlet connections
from 3/4” up to 2”.

Gas inlet pressure up to 500 mbar, air control pressure up to 120 mbar.
They are equipped with an adjustable spring and a counterspring, so that gas outlet pressure is
equal to air control pressure, with a ratio 1:1 and an adjustable offset of +/-3mbar. The offset is
useful to set gas flow at low fire.
RAG regulators have been designed for a flow regulation range equal to 10:1 and to generate
low pressure drop.

Disc is equipped with a gasket, so RAG is able to regulate precisely very low flow.
Every model is equipped with a bypass adjustable on-site. Bypass is useful in low fire state
when a very low flow is necessary or air control pressure is lower 0.5mbar.
The controls are equipped with inlet pressure compensation diaphragm for a precise regulation.
A metallic mesh filter protects the regulator seat from dirt contamination (filtration grade <1mm).
The impulse line is integrated inside the regulator. Special versions with external impulse line
are available on request.
Pipe connections meet group 2.
Suitable for use with non-aggressive gases included in the 1, 2 and 3 families (EN 437).
Special versions for aggressive gases (e.g. biogas).
Provided with pressure test points in the gas inlet, gas outlet and air control chamber to connect
manometers, pressure switches or other equipment.
RAG can be used as zero-pressure regulator. In this case it is necessary to connect the vent
port to a discharge pipe or to install the conversion kit
All components are designed to withstand any mechanical, chemical and thermal condition
occurring during typical service. Effective impregnation and surface treatments have been used
to improve mechanical sturdiness, sealing and resistance to corrosion of the components.


A ratio regulator is a device able to maintain a gas outlet pressure equal to the air control
pressure. Outlet gas and control air pressure act on the two sides of the same diaphragm,
hence the disc moves until outlet pressure is the same as air pressure. If outlet pressure is
needed to be a bit lower or higher than air, the spring must be adjusted. If a gas flow is required
to be present when air control pressure is near zero, the bypass must be set. Variation of inlet
pressure does not affect outlet pressure because the disc is compensated with a specific
In case of using the control as zero pressure regulator, it is necessary to connect vent port to a
discharge line or screw the optional kit.


Main connections Gas threaded f/f ISO 7-1 from Rp3/4 to Rp2
or ANSI-ASME B1.20 from 3/4”NPT to 2”NPT
Flanged ISO 7005 PN16 from DN25, DN40 and DN50
Air connection  G1/4” for models with Rp main threads or ISO flanges
1/4”NPT for models with NPT main threads
Pressure test points Nipples with internal screws and diameter 9 mm
Plugs with threads G1/8” (models with Rp main threads or ISO
flanges) or 1/8”NPT (models with NPT main threads)
Ambient temperature -15°C … +60°C
Gas Inlet pressure Max 500 mbar (50 kPa) or P out + 2.5 mbar for gas
P1                              Differential pressure between inlet and outlet pressure
less than 100 mbar is advisable.
Air control pressure   0.5-120 mbar
P3                                   Gas inlet pressure has to be always higher than air control pressure

Gas Outlet pressure Air control pressure +/- 3 mbar (adjustable offset)
Accuracy ±1mbar or ±15% of air control pressure (plus offset)
Max testing pressure Max 750 mbar at inlet chamber – max 200 mbar at air control
Flow capacity See charts.
Bypass flow can be set from 0 to max flow (fig.7)
Filtration grade with metallic filter <1mm
Installation 3/4”-1”: horizontal (with adjustable spring downwards)
or vertical pipeline.
1”½-2”: only horizontal (with adjustable spring downwards)
Gas type Natural gas, town gas, LPG (gaseous) of families 1,2,3 (EN437).
(for biogas see next page).

Materials in contact   Aluminum alloy, Brass, Stainless steel, plated steel
with gas                        Polyamide, Anaerobic adhesive, Nitrile rubber (NBR)

Specifications of        Free of brass.
J version                      Seals made of Fluoroelastomer (FPM) instead of NBR.
for biogas                    Ambient temperature -10/+60°.
or COG                        Max gas inlet pressure 200mbar.
Without bypass.

Couldn’t find what you were looking for?

Contact us with your specification for assessment and availability of other products configurations.

Click Here