Double
Flap Valve |
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| Double Flap valves, also known as or
double flap gates, are a type of airlock valve commonly
used in industrial applications as a component in bulk
material handling applications. Double flap valves are
primarily used to discharge chunky or fibrous, bulk
materials from hoppers, bins, and cyclones operating
under positive or negative pressure. |
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| Advantage -
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- Digidale Double flap valves are
IDEAL to discharge a flow of material while at the
same time serving as an airlock transition point to
preserve the pressure differential below the valve.
- Pressure & Dust-tight
construction.
- This type of material handling
valve is ideal for use with bulky or abrasive
materials that would tend to jam or damage a rotary
feeder.
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| Operation - |
| Double flap valves have two
trap-door flap plates which open and close on an
alternating cycle. The top gate opens to allow collected
material to drop through onto the bottom gate. The top
gate then re-closes to prevent air leakage above the
valve. The bottom gate then opens to allow material to
pass completely through the valve. The bottom gate then
re-closes to prevent air leakage below the valve. This
cycle is continuously repeated in order to maintain a
steady discharge of material from the valve, while
maintaining a positive seal on the system. |
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| Control System - |
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| Pneumatic - Each flap plate has its
own pneumatically operated cylinder and solenoid valve.
The timing of the valve is controlled by an electronic
signal sent to the solenoid valves. This method of
operation is the most expensive and allows for accurate
timing of the valve. |
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| Counterbalance - This type of double
flap valve works essentially, like a stacked pair of
trickle valves. Each flap plate is held closed with a
counterweighted arm. As material builds up on the top
plate the weight of the head of material pushes it open
where it dumps onto the bottom plate. This type of
double flap valve has no electrical or pneumatic
controls and is the least expensive method of operation.
However, it is difficult to sustain a properly timed
cycle. |
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| Cam-operated-A motor-driven cam
rotates and alternately opens the top gate and the
bottom plate. A spring attached to the gate's shaft
re-closes the gates. This type of double dump valve is
generally the most reliable and can be operated with an
electric motor . The speed of the cycle can be selected
through the gear reducer ratio or by adjusting the motor
speed. |
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| Stages - |
- Stage One:-Both Flap Closed
- Stage Two:-Upper Flap opens ,
Material pours in upper valve.
- Stage Three:-Upper Flap Closes ,
Material Collected in upper valve.
- Stage Four:-Bottom Flap opens ,
Material pours in conveying line.
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