Dover Blackmer DMX IV Manuale - Pagina 6

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4. SYSTEM CONSIDERATIONS (continued)

4.4 SETTING HIGH FLOWRATE

Adjustment MUST be made with the pump at the opera-

ting speed required for the desired flowrate and with

maximum air pressure applied to the air relief valve.

Setting of high flowrate is done by :

• Controlling the pump rpm

• Controlling the high pressure setting inside the ACP

• Controlling the line losses in the system

The high pressure setting inside the ACP controls the

maximum air pressure going to the pump air relief valve

through the DMX when the flow detector is activated.

The air pressure on the pump relief valve controls the

maximum product pressure downstream of the pump.

The flowrate will stabilize when the line losses behind

the pump equal the discharge pressure of the pump.

It is Blackmer's field experience that when a truck is desi-

gned for dual use, utilizing a 3" TXD3 Pump, the( ACP ) Air

Control Panel regulators should be set at 100 PSI on the Hi

Pressure Regulator and 50 to 55 PSI on the Low Regulator.

This will allow the pump to overcome back pressure crea-

ted utilizing 1 1/4" or 13/8" hose and nozzle.

IN CONDITIONS WHERE THE LINE LOSSES FROM THE TANK TO

THE DMX ARE EQUAL TO THE MAXIMUM INLET VACUUM

ACCEPTABLE INSIDE THE DMX, DMX WILL CREATE FLOW

CYCLING. THIS PHENOMENON WILL LIMIT THE MAXIMUM FLO-

WRATE OBTAINABLE AND MUST BE CORRECTED BY REDU-

CING THE LINE LOSSES FROM THE TANK TO THE DMX.

To increase maximum flowrate :

• Increase pump rotation speed

• Increase the setting of the high pressure regulator of

the ACP. Check in the appropriate IOM for the maxi-

mum allowable pressure to each Blackmer component.

• Reduce the line losses between the pump discharge

and the hose/delivery nozzle (increase piping diame-

ter, hose diameter, reduce number of elbows and

valves, nozzle size, reduce the length of hose, etc)..

TO AVOID DAMAGE TO THE PUMP AIR/RELIEF VALVE (9C) DO

NOT OVERPRESSURE THE RELIEF VALVE.

In cases where downstream restrictions reach the set

pressure of the relief valve before the flowrate matches

the pump speed, the pump will go into bypass and recir-

culate fluid through the pump internal relief valve.

In those situations, increasing the maximum pressure

setting of the ACP will not lead to significant flowrate

increase. Reduce the restrictions in the discharge piping.

To check for pump over speeding, position the system in

its maximum flowrate configuration (empty hose, nozzle

fully open, hose unwound from hose reel, etc.) Reduce

the pump speed by steps, allowing one minute to stabi-

lize the flowrate between each step. Record the last rpm

value before a flowrate reduction may be noticed.

Set the high pressure regulator and pump rotational

speed to limit the recirculation flowrate through the internal

relief valve.

NT 201B-A00 04.06 DMX IV Air elimination system e

NOTICE :

Some installations will require the limiting of flowrate

and/or pump discharge pressure. For example :

• To reduce the creation of foam in customer tanks

• To allow easier hose handling during delivery

Reduce the setting of the ACP high pressure regulator to

reduce the maximum flowrate.

Check the ACP IOM for the minimum differential setting

between the high pressure and low pressure setting.

After setting the regulator pressure, push down on the

air regulator adjusting knob to it lock in position.

4.5 SETTING THE FLOWRATE AND ENGINE SPEED

THE AIR RELIEF VALVE LOW PRESSURE SETTING REGULATES

THE DELIVERY HOSE PRESSURE WHEN THE NOZZLE IS CLO-

SED. ADJUST THE AIR VALVE ONLY HIGH ENOUGH TO OPEN

THE FLOW DETECTOR/CHECK VALVE AND DELIVER THE

REQUIRED LOW FLOWRATE.

At the beginning of the delivery, it is important that the

flowrate and pump discharge pressure are reduced :

• Hose handling is easier when discharge pressure is lower.

• When operating against a closed nozzle, lower dis-

charge pressure reduces horsepower required and

heat buildup in the pump.

In most operations, users will want flowrates to increase

to the maximum as quick as safely possible when delivery

is started.

In some operations, like small tank filing or topping off

tanks, users do not want high flow or high pressure. In

these cases, limit the stabilized flowrate by reducing the

opening of the delivery nozzle and do not allow the engine

speed to increase.

By controlling the setting of the DMX IV Air Elimination

System, truck acceleration and increased pump relief

valve pressure can be prevented. This may be done

without the need for a specific switch on the Truck Fuel

Delivery control panel.

To ensure that the Flow Detector is properly set :

• Determine the desired flowrate when in operation

without the engine speed being increased.

• Set the low pressure regulator of the ACP to its

lowest setting.

• Recirculate the product through the pumping system

and DMX to a tank compartment that is at least half

full and has at least 260 gallons (1000 liters) inside.

• Run the pump at the normal engine speed.

• Recirculate the fluid through the delivery hose to an

empty compartment/tank. NOTE : Remove ALL the

hose from the hose reel to reduce restrictions.

• Increase the ACP low pressure setting in 5 PSI

(0,34 bar) increments, letting the system stabilize in

flow for one minute between each adjustement.

Record the flowrate.

• The Flow detector is triggered when no air is venting

from its exhaust port. When this occurs, output 3 and

5 of the ACP should be at high pressure. If no ven-

ting occurs inside the DMX, port 4 will also be at that

high pressure.

6/15

NOTICE :