Middleby Marshall PS520G installation manual 13- Gas Control Valve

SECTION 2

INSTALLATION

1.Checking the Gas Supply (Inlet) Pressure

a. With the main gas supply valve closed and the circuit

breaker/fused disconnect in the OFF (“O”) position, open

the inlet pressure tap shown in Figure 2-13 and attach a

manometer to the tap.

b.Volumetric Method

1.Determine the time of 0.1m3 (100 liters) of gas usage as follows.

b. Depress the safety switches to allow the oven to operate.

Consumption (m3/hr.) =

NB (Rated input in kW)

c.	Open the main gas supply valve. Switch the circuit breaker/
	fused disconnect to the ON (“I”) position.
d.	Start the oven according to the directions in the Operation
	section of this Manual. Adjust the temperature controller to
	the maximum setting 600°F (316°C).
e.	Measure the supply (inlet) pressure.
f.	Switch the oven off. Close the main gas supply valve, and
	switch the circuit breaker/fused disconnect to the OFF (“O”)
	position. Remove the manometer, and close the inlet tap.
g.	Compare the measured supply (inlet) pressure to the
	nominal pressures shown in the Description section of
	this Manual.

If the supply pressure is lower or higher than the nominal pressure, the reason should be investigated and the gas supplier contacted.

For natural gas ovens, if the measured supply pressure is lower than 3.5″ wc, or higher than 7″ wc, contact the gas supplier. DO NOT OPERATE THE OVEN or adjust the oven controls.

2.Adjusting the Orifice (Manifold) Pressure and Heat Input

To use the orifice pressure method, you must know the specific gas type and quality used. If using the orifice pressure method, you should double-check the input using the volumetric method.

To use the volumetric method, you must know the heat value (HuB) of the gas used. This information is available from your gas supplier.

During these measurements, do not operate any other appliances that use the same gas meter as the oven.

a.Orifice (Manifold) Pressure Method

1.With the main gas supply valve closed and the circuit breaker/fused disconnect in the OFF (“O”) position, open the manifold pressure tap shown in Figure 2-13 and attach a manometer to the tap.

2.Remove the cap screw from the pressure adjustment screw (governor) on the gas control valve.

3.Depress the safety switches to allow the oven to operate.

4.Open the main gas supply valve. Switch the circuit breaker/fused disconnect to the ON (“I”) position.

5.Start the oven according the directions in the Operation section of this Manual. Adjust the temperature controller to the maximum setting (316°C).

6.Adjust the pressure adjustment screw as necessary to match the correct pressure for the oven's specific gas type. Refer to the Pressure Table in the Description section of this Manual. Turning the adjustment screw clockwise increases the flow, while turning it counterclockwise reduces the flow.

7.Switch the oven off. Close the main gas supply valve, and switch the circuit breaker/fused disconnect to the OFF (“O”) position. Remove the manometer, and close the manifold pressure tap.

HuB (Heat [Calorific] value

of gas in kW/m3)

Time (in minutes) of	6
	=
0.1m3 of gas usage		Consumption

2.Check that the main gas supply valve and the circuit breaker/fused disconnect are in the OFF (“O”) position.

3.Remove the cap screw from the pressure adjustment screw (governor) on the gas control valve.

4.Depress the safety switches to allow the oven to operate.

5.Open the main gas supply valve. Switch the circuit breaker/fused disconnect to the ON (“I”) position.

6.Start the oven according the directions in the Operation section of this Manual. Adjust the temperature controller to the maximum setting (316°C).

7.Adjust the pressure adjustment screw as necessary to match the calculated volume using the time (in minutes) of 0.1m3 of gas usage. Turning the adjustment screw clockwise increases the flow, while turning it counterclockwise reduces the flow.

8.Record the reading obtained from the gas meter and calculate the obtained gas flow. Compare this value to the information in the tables in the Description section of this Manual.

9.Switch the oven off. Close the main gas supply valve, and switch the circuit breaker/fused disconnect to the OFF (“O”) position. Replace the cap screw onto the gas control valve.

Figure 2-13 - Gas Control Valve

Pressure

adjustment

screw

(under cap)

Mainfold

pressure tap

(where regulated gas pressure is measured)

16