Discharge Of Exhaust Flue Products Under A Draft Hood Type A 1 Unit; How To Achieve The Nominal Thermal Capacity; Pressure Check; Checking The General Thermal Capacity - Diamond G77/6BFM11-N Handbuch

- Gas supply connection should be performed by means of metal piping of an appropriate cross section and an approved
shutoff cock should be fitted at source.
- Having connected the gas supply, you should make sure no leaks exist at the joints by checking with bubble soap.
2.5.1 DISCHARGE OF EXHAUST FLUE PRODUCTS UNDER A DRAFT HOOD. TYPE A
The gas unit should be installed under a draft hood whose system ought to have characteristics complying with Regulations.
(This unit requires a draft of at least 2cu.m/hr l kW T.C. (T.C.= Thermal Capacity).
Check kitchen aeration: it should be in compliance with law in force.
2.5.2

HOW TO ACHIEVE THE NOMINAL THERMAL CAPACITY

Check whether the unit is fitted for the gas type, pressure and category corresponding with the main gas supply.
Indication shown on packing and/or the label of the unit.
If the unit is fitted for another gas type or pressure, you need to first effect a change over to the other gas type.
See Table II for the nozzle, the idle screw (bypass), the primary air regulation, (X mm), the pilot nozzle and the nozzle pressure
for the main burner.
N.B.: The names of nozzles "2H" and "3+" are shown on the left side of Table II.
2H= G20 - 20mbar
3+= G30 29mbar and/or G31 - 37mbar coupled gas and pressure.
In our sector, we almost always have to deal with G31- 37mbar!
Table II shows the types of gas and pressure for all burners and respective nozzles, the X mm distance for the adjustment of
primary air (see Fig. 3), the idle screw (bypass), the pilot nozzle, the maximum and minimum pressure at nozzle, the maximum
and minimum thermal capacity, and the gas consumption in l/hr (15°C) or in g/hr in the case of L.P.G.
Attention: If the incoming gas' "dynamic" pressure to the unit is lower than the minimum pressure on Table II, connection is
prohibited; furthermore, the fitter should notify the gas Company that the supply pressure is too low.
N.B.: Should the pressure vary more to than +10% of the nominal pressure, e.g. for G20- 22mbar, it is advisable to mount a
pressure regulator ahead of the unit in order to guarantee the nominal pressure.
Should the supply pressure exceed the maximum pressure on Table II, e.g. for G20- 25mbar, notify the gas Company.
Make sure the inlet and nozzle pressures agrees with the values shown on Table II.
2.6

PRESSURE CHECK

INCOMING PRESSURE CHECK (Pe) Fig. 1
Pressure is measured with a manometer 0 ÷ 80mbar (precision at least 0.1mbar).
The pressure socket Fig. 1 is located on the G 1/2" gas ramp behind the panel; undo the screw (A) of the pressure socket (B),
attach the silicone rubber to the manometer, ignite the burner (Fig. 3 position 4) and take the incoming "dynamic" pressure.
Fasten the screw (A) back with a gas washer (C), check gas sealing with bubble soap.
NOZZLE PRESSURE CHECK
The pressure intake is over the nozzle (Fig. 29).
The silicone rubber is prepared for high temperatures and should be protected with tin foil to avoid its burning.
2.6.1 CHECKING THE "GENERAL" THERMAL CAPACITY
Any transformation for another type of gas (see Ch. 4) should be performed by an authorised fitter or assistant.
The thermal capacity to be checked could be:
- the nominal thermal capacity shown on the data label
- the maximum thermal capacity in the maximum position
- the minimum thermal capacity in the minimum position.
First of all, check whether the unity is already fitted for gas main and pressure; in case of transformation for operating with
other gas type, carefully check the nozzles markings, the idle screw and bypass referring to the Table II Injectors
2.6.2

ADJUSTING THE MINIMUM THERMAL CAPACITY

The right minimum for thermal capacity is achieved by means of the "calibrated" bypass idle screw firmly tightened in
accordance with Table II Injectors
Ignite the burner according to Chapter 6 "Instructions to Users" in the maximum position (
pre-heating, turn knob to the minimum position (
The oven should be heated up for at least 20 minutes by bringing the thermostat to position 8, then turn the knob to position 1.
Check the nozzle pressure and the minimum thermal capacity.
2.6.3

LIQUID GAS OPERATION CONTROL

Check whether the fitted nozzles comply with the indications on Table II,
Check whether the incoming pressure complies with the indications on Table II.
Make sure that the L.P.G. gas system has two pressure regulators of suitable capacity and that the evaporation capacity is
sufficient. See also the publication "Installation Regulations and Characteristics of L.P.G. Systems".
GB
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); after approx. 5 minutes of