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Selecting strainers

Relations:

 

1. Water flow ratio at the strainer at Δp = p₁ – p₂ = 1 bar pressure loss:

2. Pressure loss at the strainer:

Note: Select the strainer based on the nominal line diameter for flow rates up to 1 m/s.

Quantities and units:

Kv_s    m³/h        – flow ratio for different strainer diameters

Q      m³/h        – flow rate

p₁      bar           – absolute pressure upstream of the strainer

p₂      bar           – absolute pressure downstream of the strainer

Δp     bar           – pressure drop at the strainer

ρ       kg/m³      – medium density at the strainer depending on p₁ and T₁

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The strainer can be selected based on calculations or characteristic curves.

 

CALCULATION

 

 

Determine the pressure loss between the inlet and outlet port of TerFOM 80 strainer based on the following data:

Data:

Q = 10 m³/h            medium flow rate at the strainer

Procedure:

1. Determine flow ratio Kv_s:

From DN15-200 strainer data sheet

 

Specifications / Nominal diameter DN table

– flow ratio for DN80 is Kv_s = 126 m³/h

2. Determine pressure loss at the strainer:

Comments:

1. Table Technical specifications specifies Kv_s flow ratio for each DN nominal diameter. Kv_s flow ratio specifies water flow via strainer at 1 bar pressure loss between the inlet and outlet port.

2. Use Kv_s flow ratio for a specific DN nominal diameter and nominal medium flow rate to determine the pressure drop at the strainer. To simplify, the medium density ρ for water is 1000 kg/m3.

CHARACTERISTIC CURVE

 

 

Determine the pressure loss between the inlet and outlet port for TerFOM 80 strainer using the following data (example 1) from the strainer

 

Data:

Q = 10 m³/h            medium flow rate at the strainer

Strainer performance

Procedure:

1. Determine pressure loss at the strainer:

From the strainer characteristic curve:

– pressure loss at the strainer is Δp = 0.025 bar

Comments:

1. The characteristic curve shows the relation between the flow rate for each nominal diameter and the pressure loss.

Mark a known flow rate Q at the characteristic curve and determine the pressure loss Δp between the inlet and outlet port.

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