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- Elettromeccanica Delta S.p.A.
- VRA-VLA-VTA Solenoid valves for combustion air regulation
VRA-VLA-VTA Solenoid valves for combustion air regulation
VRA-VLA-VTA Solenoid valves for combustion air regulation
The VRA, VLA, and VTA are solenoid valves used for regulating cold combustion air in industrial gas burners. They are normally closed and open when energized, suitable for high/low control of combustion air.
Constructed from aluminum alloy die-cast, these valves range from DN 20 to DN 80 and comply with EN161 requirements. They are designed for continuous service, featuring two flow adjustments for high/low operation and equipped with pressure gauges.
The VRA valve opens and closes quickly, the VLA opens slowly and closes quickly, and the VTA opens and closes slowly. Flow rates can be adjusted from 0 to 100%.
Options include increased protection class up to IP65, Ex. Proof labeling, flanged connections, and a bypass bore for low fire.
Operating voltages are 230 VAC, 110 VAC, 24 VAC/DC, and 12 VAC/DC with a tolerance of -15%/+10%. They handle ambient temperatures from -15°C to +60°C and media temperatures up to +60°C, with a maximum operating pressure of 200 mbar.
Formulas for calculating flow rates and pressure drops are provided, emphasizing valve selection based on pressure drop and flow velocity.
Valves are designated by type and connection size, with additional codes for special voltages and options.
Compliant with European standards for electromagnetic compatibility and low voltage directives, with a quality management system certified to UNI EN ISO 9001.
Proper installation and periodic servicing are crucial. Detailed instructions for piping, electrical connections, and flow rate adjustments are provided.
Adjust the opening time by turning the screw on the side. A quarter turn clockwise increases the time by 2 to 3 seconds, with a maximum of about 25 seconds. The factory setting is approximately 4 seconds.
Adjustments should be made while the burner is operating. Ensure regulation remains unchanged during reassembly.
- Turn off all power before servicing.
- Inspect and replace the plug/box gasket if deteriorated.
- Ensure electrical connections are clean, dry, and tight.
- Verify valve operation by powering the coil to open and then turning off to close.
Conduct only if the valve malfunctions.
- Shut the upstream ball valve and ensure no pressure inside.
- Remove the coil and hydraulic brake if applicable.
- Check for oil leakages in the hydraulic brake and replace if necessary.
- Inspect and replace the main O-ring if needed.
- Clean the internal stem and plunger assembly.
- Inspect and replace sliding rings and sealing gaskets if necessary.
- Reassemble the valve, ensuring correct spring positioning and sealing.
- Restore pressure by opening the ball valve.
- Read installation and service instructions carefully to prevent damage and danger.
- Turn off all power before servicing.
- Do not tamper with the hydraulic brake.
- Perform functional tests after reassembly.
- Use gaskets properly to maintain warranty.
- Ensure all wiring complies with local and national codes.
- All work should be performed by qualified technicians.
Catalog excerpts
VRA VLA VTA Solenoid valves for combustion Air regulation DN20 … DN80
Open the catalog to page 1
ELEKTROGAS – Technical Sheet EE164 - 11/11 VRA VLA VTA Solenoid valves for combustion Air regulation Contents Description ………………………………………….. Features …………………………………………….. Functioning and application ………………………. Special versions and optionals ………….……….. Technical specifications …………………………… Air flow chart (pressure drop) …………………..… Ordering information …………………………….…. Standards and approvals ……………………….…. Installation, adjustment and servicing ……………. 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...
Open the catalog to page 2
ELEKTROGAS – Technical Sheet EE164 - 11/11 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. Figure 2 shows an example of installation. Air/gas ratio regulator Gas burner Gas Line Ball valve...
Open the catalog to page 3
ELEKTROGAS – Technical Sheet EE164 - 11/11 Special versions e optionals The sizes 1”¼, 1”½ and 2” can be provided with G1/4 gauges also in the outlet chamber. Protection class can be increased up to IP65. The valves will be provided with a sealed terminal box and cable set. Whole range can be provided with Ex. Proof labeling according to Directive 94/9/EC (ATEX). Whole range can be provided with electrical connection made by standard plug ISO 4400. The threaded models Rp11/2 and Rp2 can be provided with flanged connections using an optional kit. The valves can be supplied with a bypass bore in...
Open the catalog to page 4
ELEKTROGAS – Technical Sheet EE164 - 11/11 Overall dimensions ( )
Open the catalog to page 5
ELEKTROGAS – Technical Sheet EE164 - 11/11 Air flow chart (Pressure drop) 1,25 Kg/ m , 15° 1013 mbar, dry C, 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: = min. flow rate [Nm /h] = diameter of bypass bore [mm] 3 = density [Kg/m ] = relative inlet pressure [mbar]
Open the catalog to page 6
ELEKTROGAS – Technical Sheet EE164 - 11/11 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 2” solenoid valve with an air flow of 80 Nm /h there is a pressure drop ∆p = 5 mbar. 3 If we consider that 80 m /h is the flow at 200 mbar of inlet pressure, then the pressure drop to be consider is: ∆p = 5x(1+0,2) = 6 mbar Normally, pressure drop and flow rate for the valves are read from the air flow diagram. However, the valves...
Open the catalog to page 7
ELEKTROGAS – Technical Sheet EE164 - 11/11 Additional code for special voltages 110VAC Different voltage than 230V may be order adding to the standard designation the additional code as shown above. Other optionals (standard plug, bypass) must be order with their ordering code. Example: VRA62F.B for a valve with fast opening, DN50 flanged connections and 110VAC Manufacturer reserves the right to update or make technical changes without prior notice.
Open the catalog to page 8
ELEKTROGAS – Technical Sheet EE164 - 11/11 Standards and approvals The valve design meets current European approval requirements regarding electrical safety. The following standards/technical specifications have been fulfilled: - Quality Management System is certified according to UNI EN ISO 9001 and the monitoring is carried out by the notified body: Kiwa Gastec Italia Spa Via Treviso, 32/34 I- 31020 San Vendemiano (TV)
Open the catalog to page 9
ELEKTROGAS – Technical Sheet EE164 - 11/11 Installation, adjustment and servicing To assure a proper and safe operation, as well as a long life of the valve, the installation procedure and a periodical servicing are very important topics and the following instructions should be always fulfilled. IMPORTANT: before proceeding with the installation, ensure that all the features of your system comply with the specifications of the valve (media, operating pressure, flow rate, ambient temperature, electrical voltage, etc.). CAUTION Shut off the gas supply at the main manual shut-off valve and disconnect...
Open the catalog to page 10
ELEKTROGAS – Technical Sheet EE164 - 11/11 ELECTRICAL CONNECTION (IEC 730-1) Valve is provided with terminal box or standard plug (see tab. 4) for the electrical connections. To connect the valve do the following: Terminal box version: - Using a screwdriver remove the box cover. - Unscrew the gland-nut (7) and remove the retaining ring (9) and conical grommet (5). - Insert the cable in to the gland-nut, retaining ring, grommet and then into its housing in the box cover. - Connect power cables to the rectifier terminals (1) according to printed designation. - Pull the cable and screw back the...
Open the catalog to page 11
ELEKTROGAS – Technical Sheet EE164 - 11/11 VRA MAX. FLOW RATE ADJUSTMENT (Vmax) Maximum flow rate may be adjusted as follows: 1. Remove coil fastener cap on the top. 2. Using a 4 mm Allen wrench, remove the locking dowel. 3. Located under the locking dowel is the Max. flow regulation screw. Using the Allen wrench, turn the Max. flow regulation screw clockwise to decrease the Max. flow rate (factory setting is max. flow rate). 4. When adjustment is completed, screw back the locking dowel and cap. MIN. FLOW RATE ADJUSTMENT (Vmin) Minimum flow rate may be adjusted as follows: 1. Using a 4 mm Allen...
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