DUNGS GW 150 A6 Gas Pressure Switch 5-150 mbar

Overview

The DUNGS GW 150 A6 is the 5 to 150 mbar member of the Karl Dungs GW A6 range of compact pressure switches for gas, air, flue gas and exhaust gas. It is the range most often used as a minimum or maximum gas pressure switch on commercial burner gas trains, because a typical low-pressure supply and the head pressure of a forced-draught burner both sit comfortably inside 5 to 150 mbar. The switch is built to EN 1854 as a class S pressure switch and carries the GW 150 A6 marking directly on its scaled setting dial, which makes field identification simple.

Seven Star LLC supplies the DUNGS GW 150 A6 to boiler service companies, burner manufacturers and plant maintenance departments in Oman and the GCC, with engineering support in Muscat. Our Dungs GW A6 Compact Pressure Switch for Gas and Air page explains the whole GW A6 family; this page concentrates on the 150 mbar range, its order numbers and the data that matter when replacing a failed switch on a running plant.

Operating Principle

The DUNGS GW 150 A6 is a single-acting overpressure switch. The medium acts on an NBR diaphragm whose force is balanced against a spring preloaded by the adjusting wheel. When the pressure rises above the set value, contact 1 (normally closed) opens and contact 2 (normally open) closes; when the pressure falls back, the contacts return. The switch needs no auxiliary power, so the pressure itself operates the silver changeover contact. For the 150 mbar range the datasheet gives a switching difference of no more than 5 mbar at the lowest setting and no more than 10 mbar at the highest setting, with a setting tolerance of plus or minus 15 percent of the set value.

On a gas train the DUNGS GW 150 A6 is usually wired as a minimum gas pressure switch: if the connection pressure falls below the setting, the switch opens the burner control circuit and prevents a start, or stops the burner during operation. As general practice, a burner manual such as the Bentone BG 400 manual instructs the technician to measure the connection pressure at full load and set the minimum switch about 10 to 15 percent below it, then confirm the trip point by slowly closing the ball valve. The same unit wired on the normally closed contact can act as a maximum pressure switch downstream of a regulator.

Engineering Design of the DUNGS GW 150 A6

The housing of the DUNGS GW 150 A6 is aluminium die cast, the switch part is polyamide, the diaphragm is NBR and the contacts are silver. In the standard V0 design the pressure connection is a G 1/4 internal thread in the centre of the housing bottom; the designation GW 150 A6 [Ag-G3-MS9-V0-VS3] used in the datasheet example adds a sealing screw at a second G 1/4 position on the side. A test nipple of 9 mm diameter is integrated in the metal housing so the actual pressure at the switch can be measured during commissioning. Mounting kits allow the switch to be fitted directly to DUNGS SV solenoid valves, or two switches to be combined as a double pressure switch.

Electrical connection of the DUNGS GW 150 A6 is a 3-pin terminal connector for line sockets to DIN EN 175 301-803, protection-insulated without an earth connection, giving IP 54. The standard installation position has the diaphragm vertical. If the DUNGS GW 150 A6 is mounted horizontally, the datasheet states that the switching point shifts by approximately 1 mbar: upward when installed horizontally, downward when installed horizontally overhead. On the 150 mbar range this offset is small, but it is still worth allowing for when the setting is close to the actual supply pressure.

Key Features

The DUNGS GW 150 A6 offers these practical benefits on burner gas trains and air systems:

• The setting range of 5 to 150 mbar covers most low-pressure natural gas and LPG vapour supply duties.
• The maximum operating pressure of 500 mbar gives a wide safety margin above the setting range.
• The changeover contact provides both normally closed and normally open functions from one device.
• Nominal current is up to 10 A AC, with a switching current of up to 6 A at cos phi 1 and 3 A at cos phi 0.6.
• An integrated test nipple allows the pressure at the switch to be checked without extra fittings.
• The switch works without auxiliary power, which keeps the safety chain simple.
• Ambient and medium temperature limits of minus 15 to plus 70 degrees Celsius suit typical boiler rooms.
• Approval to EN 1854 class S is covered under the EU Gas Appliances Regulation and Pressure Equipment Directive.

Industrial Applications

Typical uses of the DUNGS GW 150 A6 include minimum gas pressure monitoring on MultiBloc and double solenoid valve gas trains, maximum gas pressure protection downstream of a regulator, and pressure monitoring on air and flue gas ducts. It is suitable for gases of families 1, 2 and 3 and other neutral gaseous media. The damped GW 150 A6/1 variant, with a nozzle in the pressure connection, is available where pulsating pressure would otherwise cause nuisance trips.

In Oman the DUNGS GW 150 A6 is found on boiler burners in hotels and hospitals in Muscat, on industrial kitchens and bakeries, and on process heaters in the Sohar and Salalah free zones. Seven Star LLC supplies it together with matching items such as the Dungs SV-D 505 Safety solenoid valve Nominal width Rp 1/2 – Rp 2, the DUNGS DMV-D 507/11 Double Solenoid Valve and the DUNGS VPS 504 219881, giving maintenance teams in the GCC one source for burner safety components.

Technical Specifications

The data below for the DUNGS GW 150 A6 are taken from the manufacturer datasheet for the GW A6 series attached to this page.

How to Order

To order the DUNGS GW 150 A6, send Seven Star LLC an RFQ with the order number or the text on the dial, the quantity and any line socket or mounting kit you need. Our team in Muscat confirms the version against the attached datasheet and arranges delivery to sites across Oman and the GCC.