Micron Technology Turbofan instruction manual Draft, 4.2.4Hydraulic Oil Flow

DRAFT

To calculate the hydraulic flow required for a specific number of Turbofan Sprayheads running in series pairs:

•Each head and each chain runs at 8.0 l/min

•Allow 10% for pump and other hydraulic losses. Therefore flow per chain (ie 2 x Turbofan) = 8.8 l/min

• Therefore for 6 heads (3 chains of 2) the flow required = 8.8 x 6 = 26.4 l/min 2

Alternatively if you know the maximum hydraulic flow available (and the system pressure is 200 bar or above) then :

Maximum number of heads which can be fitted	= 2 x maximum hydraulic flow available
with 2 motors in series in each chain	8.8

e.g. If flow available = 72 l/min

then maximum number of heads in series (two per chain) = 2 x 72 = 16.4 = 16 heads 8.8

4.2.4Hydraulic Oil Flow

If a Power Take Off (PTO) driven hydraulic pump is used, the pump should be chosen to provide the calculated maximum oil flow plus losses and no more. If a larger pump were to be used, any unused oil would have to be by-passed and would generate heat.

The specified output of the pump must match the calculated oil requirement (see sample calculations in Sections 4.2.2 and 4.2.3)

When calculating pump output, ensure that the actual operating speed of the tractor is taken into account. Many pumps are specified at 540 rpm nominal PTO speed. Most tractors are driven at an engine speed corresponding to a lower PTO speed. For example, if running at 500 rpm a pump rated at 100 l/min at 540 rpm will actually produce:

100 l/min x 500 rpm (actual) = 92.6 l/min

540 rpm (nominal)

4.2.5Hydraulic Pressure and Hose Size Selection

When designing a system and selecting a pump, the additional pressure drop across all hoses and fittings must be taken into account. The working pressure of all components must be adequate for worst-case conditions, including start-up pressure surges.

All hoses, pipes and fittings must be chosen to give an acceptably low pressure drop at the maximum operating flow rate. The procedure to select the sizes of the pressure and return lines is as follows:

a)On all pressure lines – calculate flow through each section, then use the design table (Table 1) to select the appropriate diameters so that the total pressure drop along any route from the pump to a sprayhead does not exceed 3.0 bar (45 psi).

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