Membrane Filter Elements
36 Operating Manual Status: 06/2001/01
Squeezing pressure rise with compressible media
So that the squeezing pressure rises in accordance with the specified limit, a throttle plate
or throttle valve must be installed in the supply line.
Its sizing is determined by the dewatering rate of the product. If a throttle plate is installed,
begin with the smallest possible diameter and then adapt gradually during commissioning
while observing the permissible pressure rise.
Squeezing volume flow
The squeeze volume flow may be intermittent. The peak requirement is generally three to
ten times higher than the average value.
Venting
The membrane filter elements must be continuously bled to the atmosphere (does not apply
during squeezing).
Following squeezing, the squeeze air must be completely reduced to the ambient air
pressure.
Therefore, a valve with an appropriately large cross section is connected to the manifold to
quickly release the squeeze air. For safety reasons, the valve must be open when de-
energised.
Example
Chamber volume = 2 m³
Chamber depth = 40 mm
Final cake thickness = 30 mm
Squeezing time = 25 min
Squeezing pressure = 10 bar
Peak requirement = factor 5 x average
Air requirement = approx. 10/40
∗ 2 m³ ∗ 10 m³
N
/m³ = 5.0 m³
N
Required flow rate = approx. 5.0 m³
N
/25 min ∗ 5 = 1.0 m³/min
Warning
With the exception of the squeezing time, the vent valve must be continuously open. The
valve must be integrated in the safety chain of the filter press controller in such a way
that in the case of a power failure, pressure loss in the hydraulic system or other
potentially dangerous conditions during squeezing the squeeze air can be vented
immediately and the supply interrupted by the shut-off valve.
Observe the accident prevention regulations and the execution instructions for filter
presses from "BG-Chemie" or the national or international safety regulations applicable
for your company.
WARNING
