Simon Anthes
Application Manager AquaCulture
Phone: +45 4129 4898
Why Correct Pump Piping Matters
By Simon Anthes, Senior Application Manager at DESMI
Centrifugal pumps are often blamed when systems underperform. In reality, the pump is rarely the problem. The piping connected to it is.
In land-based aquaculture facilities - particularly large RAS systems - poor inlet piping design can reduce pump performance by 20–40%, increase energy consumption, and shorten equipment lifetime.
That is why the European standard CEN 13932 exists. It defines how piping systems should be arranged around centrifugal pumps to ensure stable hydraulic conditions.
Why This Matters in Aquaculture
Water circulation is the backbone of a land-based farm. Every subsystem relies on stable flow:
- Mechanical filtration
- Biofiltration
- Oxygenation
- Degassing
- Temperature control
If the pump operates under unstable hydraulic conditions, it can lead to:
- Flow fluctuations
- Increased vibration
- Cavitation risk
- Reduced pump efficiency
- Higher maintenance costs
In systems circulating thousands of cubic meters per hour, even small inefficiencies become expensive.
The Core Principle: Stable Flow Into the Pump
Centrifugal pumps are designed to receive uniform, non-turbulent flow at the impeller eye.
Disturbed inlet flow causes:
- uneven impeller loading
- hydraulic imbalance
- internal recirculation
This reduces efficiency and increases wear.
CEN 13932 therefore recommends proper inlet piping arrangements.
Optimum pump installation
Recommended design of pipes on suction side (AI-generated images)
Key Recommendations From CEN 13932
1. Provide sufficient straight pipe before the pump
A common recommendation is:
5–10 pipe diameters of straight pipe
before the suction flange.
This stabilizes velocity distribution.
2. Avoid elbows directly at the pump inlet
An elbow immediately before the pump introduces swirl and asymmetric flow, which the impeller is not designed to handle.
3. Avoid sudden diameter changes
Reducers should be eccentric reducers with flat top orientation to prevent air pockets; however concentric reducers are fine for vertical inlets.
4. Prevent air accumulation
Entrained air dramatically increases cavitation risk.
Design should avoid:
- high points before the pump
- air traps
- poorly vented suction lines
The Hidden Cost of Bad Piping
Many pumping problems attributed to pump manufacturers are actually caused by:
- poor suction piping
- incorrect reducers
- insufficient straight length
Fixing these can often deliver double-digit energy savings without changing the pump.
In an industry where energy is one of the largest operating costs, this matters.
Takeaway
A centrifugal pump cannot perform better than the hydraulic conditions it receives.
Following CEN 13932 ensures:
- stable pump operation
- higher efficiency
- longer equipment lifetime
- lower operational cost
And in aquaculture systems operating 24/7, those gains accumulate quickly.