Macnaught FTWM120-001, Инструкция по эксплуатации

Страница: 11 / 20

5. CONSIDERATIONS REGARDING DELIVERY AND SUCTION LINES
DELIVERY
1. The choice of pump mode must be made keeping the characteristics of the system in mind.
2. The combination of the length of the tubing, the diameter of the tubing, the flow rate of the
diesel fuel and the line accessories installed can create back pressure greater than the
maximums anticipated such as to cause the (partial) opening of the pump by-pass with the
consequent noticeable reduction of the flow rate supplied.
3. In such cases, to allow correct functioning of the pump, it is necessary to reduce system
resistance, using shorter tubing and/or of wider diameter and line accessories with less
resistance(e.g. an automatic dispensing nozzle for greater flow rates).
SUCTION
1. All pumps are self-priming pump and characterized by good suction capacity.
2. During the start-up phase, with an empty suction tube and the pump wetted with fluid, the
electric pump unit is capable of suctioning the liquid with a maximum difference in height of 2
meters. It is important to point out that the priming time can be as long as one minute and
the pressure of an automatic dispensing nozzle on the delivery line prevents the evacuation
of air from the installation, and, therefore, prevents proper priming.
3. For this reason, it is always advisable to prime the pump without an automatic delivery
nozzle, verifying the proper wetting of the pump. The installation of a foot valve is recom-
mended to prevent the emptying of the suction tube and to keep the pump wet. In this way,
the pump will subsequently always start up immediately.
4. When the system is functioning, the pump can work with pressure at the inlet as high as 0.5
bar, beyond which cavitation phenomena can begin, with a consequent loss of flow rate and
increase of system noise.
5. As we have said up to this point, it is important to guarantee low suction pressure by using
short tubing of a diameter equal to or larger than recommended, reducing curves to a
minimum and using suction filter of wide cross-section and foot valves with the lowest
possible resistance.
6. The difference in height between the pump and the fluid level must be kept as small as
possible and, at any rate, within the 2 meters anticipated for the priming phase.
7. If this height is exceeded, it will always be necessary to install a foot valve to allow for the
filling of the suction tube and provide tubing of wider diameter. It is recommended that the
pump not be installed at a difference in height greater than 3 meters.
In the case that the suction tank is higher than the pump, it is advisable to install an
anti-siphon valve to prevent accidental diesel fuel leaks.
INITIAL START-UP
• Check that the quantity of diesel fuel in the suction tank is greater than the amount you wish
to transfer.
• Make sure that the residual capacity of the delivery tank is greater than the quantity you wish
to transfer.
• Do not run the pump dry. This can cause serious damage to its components.
• Make sure that the tubing and line accessories and in good condition. Diesel fuel leak can
damage objects and injure person.
• Never start or stop the pump by inserting or removing any plugs.
• Do not operate switches with wet hands.
• Prolonged contact with diesel fuel can damage the skin. The use of glasses and gloves is
recommended.
E9