Datasheet Content
VRA
VLA
VTA
Solenoid valves for
combustion Air regulation
DN20 … DN80
delta-elektrogas.com EE164 -05/14
ELEKTROGAS – Technical Sheet EE164 - 05/14
VRA
VLA
VTA
Solenoid valves for
combustion Air regulation
Contents
Description ………………………………………….. 2
Features …………………………………………….. 2
Functioning and application ………………………. 3
Technical specifications …………………………… 4
Air flow chart (pressure drop) …………………..… 6
Ordering information …………………………….…. 8
Special versions and optionals ………….……….. 8
Design, installation and servicing ……………. 9
Standards and approvals ……………………….…. 10
Description The VRA/VLA/VTA types are normally closed solenoid valves for cold combustion air regulation
(open when energized). This type of device is suitable for high/low control of combustion air in
industrial gas burners.
Features The valves are made of aluminum alloy die-cast, with a wide range for inlet/outlet connections
from DN 20 up to DN 80.
Pipe connections meet group 2, according to EN161 requirements.
Suitable for use with cold combustion air (not for safety purposes).
Provided with two flow adjustments: minimum and maximum flow rate, for high/low operation.
Suitable for heavy duty cycle operation and for continuous service (100% ED).
The whole range can be provided in Ex-proof execution, for use in Zones 2 and 22, according to
94/9/EC Directive (ATEX).
The valve is supplied without an internal filter, because in many applications the air is very dirty
and it should clog the filter in short time. It is provided with a special dust cover able to protect
mechanical moving parts.
Provided with G1/4 pressure gauge on two sides in the inlet chamber, to connect manometers,
pressure switches or other equipments. Flanged models are provided with gauges also in the
outlet chamber.
The coils are provided with terminal box or with ISO 4400 plug (optional). Both systems are
provided with suitable cable gland to avoid water and dirty contamination.
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.
Valves are 100% tested by computerized testing machineries and are fully warranted.
WARNING
This control must be installed in compliance with the rules in force.
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ELEKTROGAS – Technical Sheet EE164 - 05/14
Functioning and
application The VRA type valve is a fast opening/closing solenoid valve. The VLA type is a slow opening an
fast closing solenoid valve. The VTA type is a slow opening/closing solenoid valve.
Both Min./Max. can be set from 0 to100%.
When not energized the spring works on the disc keeping the minimum passage of air. When
powering the coil the valve opens, moving the disc to the maximum open position. When power
is switched off the valve moves to the minimum position.
Min. Flow Max. Flow
Fig.1
Figure 2 shows an example of installation.
Gas
filter Air/gas ratio
regulator
Gas
Gas burner
Line
Ball
valve Gas solenoid
valve
Air solenoid
valve Adjusting
cock
Air
Line
Fig.2
WARNING
This is not a safety valve.
Location and mode of installation must be in compliance with local rules in force.
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ELEKTROGAS – Technical Sheet EE164 - 05/14
Technical
specifications Tab. 1
Connections Gas threaded ISO 7-1 from Rp3/4 to Rp2½
Flanged PN16 – ISO 7005 from DN40 to DN80
Voltage rating 230 VAC 50/60 Hz
110 VAC 50/60 Hz
24 VAC/DC
12 VAC/DC
Voltage tolerance -15% / +10%
Power consumption see charts
Ambient temperature -15°C / +60°C
Media temperature +60°C Max.
Max. operating pressure 200 mbar (20 kPa)
Flow capacity see charts
Operating time VRA: 1s opening/closing
VLA: ~4s opening / 1s closing
VTA: ~4s opening/closing
Protection class IP54 (EN 60529)
(optional IP65)
Cable gland M20x1,5 (EN 50262) for terminal box
PG 9 for standard plug
Coil winding insulation Class H (200°C)
Coil thermal resistance Class F (155°C)
Materials in contact Aluminium alloy
with media Brass
Stainless steel
Plated steel
Anaerobic adhesive
Nitrile rubber (NBR)
Polytetrafluoroethylene (PTFE)
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ELEKTROGAS – Technical Sheet EE164 - 05/14
Fig.3
Tab. 2
4 3
Connections Power Flow factor Overall dimensions ( ) Weight ( )
Consump. Kvs
@230VAC [m³/h] [mm]
[W] A B C D E Int h [Kg]
Rp 3/4 25 8,3 88 96 145 179 54 - - 2,5 / 2,7
Rp 1 25 10,5 88 96 145 179 54 - - 2,5 / 2,7
2
Rp 11/4 45/180 ( ) 20,0 120 153 191 235 70 - - 5,7 / 6,0
2
Rp 11/2 45/180 ( ) 26,0 120 153 191 235 70 - - 5,7 / 6,0
2
Rp 2 45/180 ( ) 32,0 106 156 195 245 70 - - 6,0 / 6,3
2
Rp 2½ 45/180 ( ) 56,0 180 218 254 315 70 - - 12 / 12,5
1 2
DN 40 ( ) 45/180 ( ) 26,0 150 193 191 266 70 110 4x18 7,4 / 7,7
1 2
DN 50 ( ) 45/180 ( ) 32,0 165 196 195 278 70 125 4x18 8,0 / 8,3
2
DN 65 45/180 ( ) 56,0 200 305 266 355 70 145 4x18 14,0 / 14,5
2
DN 80 45/180 ( ) 66,0 200 305 266 355 70 160 8x18 14,0 / 14,5
1 2 3 4
( ) Optional Kit ( ) Working/Opening ( ) VRA/VLA ( ) VTA type: E+10
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ELEKTROGAS – Technical Sheet EE164 - 05/14
Air flow chart
(Pressure drop)
3
1,25 Kg/ m , 15°C, 1013 mbar, dry
If requested, the valves can be supplied with a bypass bore in the valve body for low fire.
The diameter must be chosen according to the min. flow rate required. The approximate formula
to calculate the flow rate is the following:
p1
Vmin = 0.024 ⋅ d2
ρ
where:
3
Vmin = min. flow rate [Nm /h]
d = diameter of bypass bore [mm]
3
ρ = density [Kg/m ]
p1 = relative inlet pressure [mbar]
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ELEKTROGAS – Technical Sheet EE164 - 05/14
When the flow read on the diagram is referred to operating pressure instead of standard
conditions, the pressure drop ∆p read on the diagram must be multiplied for the factor
(1+ relative pressure in bar).
Example:
3
In the VRA62 2” solenoid valve with 70 Nm /h of airflow the pressure drop is ∆p = 6 mbar.
3
If we consider that 70 m /h is the flow at 200 mbar of inlet pressure, then the pressure drop to
be consider is:
∆p = 6x(1+0,2) = 7,2 mbar
Normally, pressure drop and flow rate for the valves are read from the air flow diagram.
However, the valves can also be chosen in accordance with the characteristic ”Kvs value” which
is shown in table…
