day tanks are the fuel containment systems designed for installation in combination with a motor to provide a reliable supply of diesel fuel. They are often required when the engine-mounted fuel pump is able to draw fuel from a remote fuel tank mounted because of distance or elevation problems. For safety and reliability, these power systems are configured as suction-type, which means that the daily tank draws fuel from the main tank, and the engine draws fuel from the day tank.
There are no fundamental differences in the configuration of these systems when used with above ground storage tanks (AST) or under-ground storage tanks (UST). There are also important considerations regarding accessories of the tank.
Integration with AST - in this type of application, you must pay attention to the elevation of the day tank to the main AST. Because of the ability to siphon between day tank and AST, some components must be installed in the fuel pipe. Typically, a solenoid valve and filter are installed on the pump of the tank. This is a solenoid valve that will be normally closed. It opens only when the tank level is detected to be low, at this point the solenoid valve is opened and the feed pump is energized. Since the tank reaches a maximum level, the solenoid valve and the pump are de-energized, which stops the flow of fuel and closes the fuel inlet in the tank. Additional components that are recommended in these systems are ball valves and manually operated fuse valves that close automatically in case of fire. These should be installed at the input and the output of the tank to allow isolation of the emergency equipment or regular scheduled maintenance purposes.
A well-designed system requires that the day tank is able to return any excess fuel to the AST. The failure to arrest a filling pump or close a solenoid valve could cause the continuous filling of the tank. Without the means to return excess fuel, leakage is inevitable. The return overflow pump is generally mounted on the tank and must be dimensioned to exceed the supply pump. Its output must be equipped with a control valve to prevent backfeed when the return pump stops.
Some applications will have the AST in a remote location that is too far away for the day tank fuel pump to draw reliable. In these cases, the daily tank is equipped with an overflow pump, and a self-powered pump is mounted close to the main draw fuel from the tank AST and push it to the day tank. The remote pump would still interface with the tank level controller to receive the start / stop signals.
Integration with UST - in this type of application, consideration should be given to the possibility that the day tank fuel pump could lose his first. For this reason, a foot valve is generally installed on the main tank, and a hand pump, check valve and the solenoid valve are installed on the day tank. The hand pump allows the emergency filling and also provides the means to restore raw fuel on the line supplying the motor-driven pump. The check valve and acting solenoid valve to limit any reflux to the main FSO. In UST, overflow applications (return) fuel is mostly conveyed from the tank daily UST and gravity is sufficient to prevent flooding of the day tank. As in AST drawings, if the daily tank too far from the FSO, the supply pump must be positioned by the FSO.
configuration General Recommendations - These additional recommendations to be considered for a properly configured system:
1. To insist not only UL142 compliant day tanks, but also in the UL508-compliant checks.
2. Size of the tank for a minimum of 2 hours of runtime engine, without the need for recharging.
3. The feed pump must be dimensioned to three times the fuel consumption at full load of the engine (or engines if the tank feeds several motors). In the example above (0GPH or consumption 2GPM), the pump must be sized to a minimum 6GPM.
4. The return pump (if applicable) must be dimensioned to exceed the capacity of the feed pump.
5. Format all accessories (such as ball valves, solenoid valves, etc.) not less to fuel lines that connect to accessories.
6. Specify double-walled construction with sensor break detection of reservoir leakage. This sensor is interconnected to the supply pump to stop operation in case of a leak in the primary containment. The controller should also indicate the condition with a visual alarm.
7. Always specify that the covers of appropriate pressure relief vent be included with the tank. These allow for the emergency vent when normal atmospheric vent clogged. In indoor installations, the working vent must be piped to the outside.
8. Review the competent local authorities (AHJ) to see if the controls and accessories should be powered by the engine battery (eg 24 V DC) or if an emergency attachment circuit 0Vac would be acceptable.
9. The most diesel engines attract more fuel than is required for combustion. The excess fuel is typically returned to the day tank. Depending on the fuel efficiency rate, it may be necessary to consider transferring it to the main, or you may need to design your system with a greatest day tank or a fuel cooler to prevent the fuel supply heating tank fresh. heated fuel will decrease rated power of the engine, and can lead to engine stop if the building loads exceed the power of the engine capacity.
10. application prime-duty, increase system reliability by specifying a duplex feed pump set with pump body in cast iron and steel rotors. Duplex pumps allow early / late or simultaneous operation by the operator. The duty pump in heavy cast iron will last longer and produce less operating noise.
11. Insist on the following local and remote alarms from the provider:
a) low level alarm and annunciation output contact distance.
b) a high level alarm and annunciation output contact distance.
c) high-level critical alarm, the pump off and annunciation output contact distance.
d) Low critical level alarm, engine shutdown (prevents loss of primary fuel) and annunciation output contact distance.
e) alarm of the tank leak detection and annunciation output contact distance.
The guidelines above can help you with choosing the right product for the application. However, it is advisable to contact the supplier to review all the options or accessories that may be needed to ensure reliable and safe operation of a specific application of the power supply. Additional resources related Friends For day to fuel tanks and related systems Friends, you can visit Http://www.hurtado.cc/resources.htm .
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