Middleby Marshall Model PS536 - Manual (Page 19)

19
ENGLISH
SECTION 2 - INSTALLATION
D. Checking the Gas Supply (Inlet) Pressure
1. Remove the supply (inlet) pressure cap screw from the gas
control valve. Attach a manometer to the stud.
2. Depress the safety switches to allow the oven to operate.
3. Open the main gas supply valve. Switch the circuit breaker/
fused disconnect to the ON ("I") position.
4. Start the oven according the directions in the Operation
section of this Manual. Adjust the temperature controller to
the maximum setting (316°C).
5. Measure the supply (inlet) pressure.
6. 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 replace the cap
screw onto the gas control valve.
7. Compare the measured supply (inlet) pressure to the
nominal pressures shown in Table 1-5 (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 17mbar, or higher than 25mbar, contact the gas supplier.
DO NOT OPERATE THE OVEN or adjust the oven controls.
E. 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.
1. Orifice (Manifold) Pressure Method
a. Check that the main gas supply valve and the circuit
breaker/fused disconnect are in the OFF ("O") position.
b. Remove the regulated (manifold) pressure cap screw
from the gas control valve. Attach a manometer to the
stud.
c. Remove the cap screw from the pressure adjustment
screw (governor) on the gas control valve.
d. Depress the safety switches to allow the oven to
operate.
e. Open the main gas supply valve. Switch the circuit
breaker/fused disconnect to the ON ("I") position.
f. Start the oven according the directions in the Operation
section of this Manual. Adjust the temperature controller
to the maximum setting (316°C).
g. Adjust the pressure adjustment screw as necessary
to match the correct pressure for the oven's specific
gas type. Refer to Table 1-5 in the Description section
of this Manual. Turning the adjustment screw clockwise
increases the flow, while turning it counterclockwise
reduces the flow.
h. 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
replace the cap screws onto the gas control valve.
Consumption (m 3 /hr.) =
NB (Rated input in kW)
HuB (Heat [Calorific] value
of gas in kW/m3)
=
Time (in minutes) of
0.1m3 of gas usage
2. Volumetric Method
a. Determine the time of 0.1m 3 (100 liters) of gas usage
as follows.
6
Consumption
b. Check that the main gas supply valve and the circuit
breaker/fused disconnect are in the OFF ("O") position.
c. Remove the cap screw from the pressure adjustment
screw (governor) on the gas control valve.
d. Depress the safety switches to allow the oven to
operate.
e. Open the main gas supply valve. Switch the circuit
breaker/fused disconnect to the ON ("I") position.
f. Start the oven according the directions in the Operation
section of this Manual. Adjust the temperature controller
to the maximum setting (316°C).
g. Adjust the pressure adjustment screw as necessary
to match the calculated volume using the time (in
minutes) of 0.1m 3 of gas usage. Turning the
adjustment screw clockwise increases the flow, while
turning it counterclockwise reduces the flow.
h. Record the reading obtained from the gas meter and
calculate the obtained gas flow. Compare this value
to the information in Table 1-4 in the Description
section of this Manual.
i. 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.