Casella Apex 2 - Back Pressure Explanation

Apex2
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What is back pressure?
This is the resistance to flow caused by the filter media as opposed to free flow of air
through the pump (like having a sock over your vacuum cleaner nozzle, the pump has to
work a bit harder!). Back pressure is measured in inches or cm of water. The smaller the
pore size of your filter, the greater the back pressure and the harder the pump has to work.
As well as being a drain on the battery the pump needs to be powerful enough to overcome
the resistance. Another factor is the flow rate and it is the combination of flow rate and filter
media that determines the back pressure.
Having a pump that is capable of dealing with a wide variety of flow rates and filter media is
really important and the Apex2 has class beating back pressure capability. Please refer to the
table below for typical back pressures exerted by particular filter media.
25 mm MCE/0.8
25 mm MCE/0.45
37 mm MCE/0.8
37 mm PVC/5.0
37 mm
Polycarb/0.45
37 mm PTFE/1.0
Flow rate
ml/min
inches
cm
inches
cm
inches
cm
inches
cm
inches
cm
inches
cm
1000
6
15.24
14
35.56
2
5.08
1
2.54
4
10.16
1.5
3.81
1500
9
22.86
22
55.88
3
7.62
1
2.54
6
15.24
2.5
6.35
2000
12
30.48
28
71.12
4
10.16
2
5.08
8
20.32
4
10.16
2500
15
38.1
35
88.9
5
12.7
2
5.08
10
25.4
5.5
13.97
3000
18
45.72
40
101.6
6
15.24
2.5
6.35
12
30.48
7
17.78
3500
21
53.34
44
111.76
7
17.78
3
7.62
15
38.1
8
20.32
4000
25
63.5
50
127
9
22.86
3
7.62
17
43.18
9.5
24.13
5000
31
78.74
63
160.02
11
27.94
4
10.16
21
53.34
12
30.48