High-volume pressure testing systems are not primarily a pump sizing issue; rather, they are a system architecture decision.
When large filling volumes meet high test pressures and dynamic load profiles, the configuration of the pressure testing system affects hydraulic performance, connected load, infrastructure requirements, and overall efficiency. This article compares single-pump and staged multi-pump architectures, analyzing their impact based on a verified application case.
Why High-Volume Pressure Testing Systems are a System Issue
Hydrostatic pressure testing of large components, such as large pipes, pipeline sections or very large pressure vessels, exhibits a common pattern: a large volume, a high final pressure and a highly dynamic test cycle. It is precisely this load profile that makes designing a pressure testing system so challenging.
First, the system is filled at a moderate pressure. This is followed by one or more pressure ramps, maintenance of the final pressure and, finally, controlled relief. All of these steps must be carried out with stable control quality, reproducible pressure control and safe system behaviour.
In practice, this requirement profile is often met using a single, very large high-pressure pump. While this is technically functional, it is not necessarily the most efficient system solution when considering factors such as connected load, mains connection and availability.
An alternative is the staged multi-pump architecture, in which several high-pressure pumps with staged pressure and delivery characteristics share the test cycle, ensuring that each pump operates within its most efficient range. This is precisely the principle behind the KAMAT concept for high-volume pressure testing systems.
The Single Pump is Functional but Often Oversized in the Real Cycle.
In a pressure testing system, a large single pump must cover two extremes simultaneously.
- A high flow rate for fast filling at low to medium pressure.
- High pressure at the end of the pressure ramp and in the holding phase (at a significantly lower flow rate).
Consequently, the pump operates outside its optimum operating point for a large part of the test cycle. This has several effects:
- poorer efficiency in partial load operation;
- low flexibility at very low flow rates;
- no real redundancy in the pump train.
This architecture often leads to unnecessarily high installed power consumption, especially in high-volume pressure testing systems with dynamic load profiles.
Multi-Stage Multi-Pump Architecture in the Pressure Testing System
“Every pump where it is strong.”
In a multi-stage, multi-pump architecture, the work of the entire test cycle is shared between several pumps.
- First, the high-volume pumps fill up rapidly to a defined pressure level.
- Then, pumps for higher pressure ranges take over.
- Finally, a smaller high-pressure pump achieves the final test pressure.
Since each pump only covers the pressure range for which it is designed, it operates closer to its optimum efficiency.
Valve station as a central control element
To ensure that this pressure staging functions cleanly, safely, and reproducibly, the valve station is a central component of the pressure testing system.
It provides the control-relevant parameters and contains controllable pressure relief valves for each pressure stage. This controls the transitions between the stages and reliably ensures protective functions in each phase.
Practical Example: Same Hydraulic Requirements, Significantly Lower Connected Load
In the verified example, the following target values were considered:
- Maximum test pressure: 690 bar
- Total flow rate: 413 l/min
The hydraulic target requirements are identical for both concepts. Both the multi-stage, multi-pump pressure testing system and the single-pump solution can achieve a pressure of 690 bar at a flow rate of 413 litres per minute.
Concept A – Multi-stage multi-pump solution
Example pump distribution:
Total installed power consumption of the multi-pump pressure testing system: 336 kW
Important: the total flow rate of 413 l/min is not achieved by a single pump, but rather through the staggered operation of the pressure stages.
The pumps only operate within their designed pressure range. Unnecessary units are switched off during the cycle.
Concept B: Single pump solution
For comparison, a single pump with identical hydraulic target requirements was considered:
- Pump type: K100050
- 690 bar
- 413 l/min
Installed power consumption: 850 kW
The entire hydraulic range is covered by a single machine.
Result:
With identical hydraulic target requirements (690 bar/413 l/min), the staged multi-pump architecture reduces the installed connected load by 514 kW.
- High-volume pumps operate in the lower pressure range with high efficiency
- Medium-pressure and high-pressure pumps are only switched on when they are needed
- Unnecessary units are switched off
This prevents a large single pump from being operated continuously outside its optimum operating point
Zusätzliche Ergebnisse aus dem Druckaufbau-Vergleich
In addition to the installed connected load, cycle-related key figures were also examined in the comparison.
1️. Pressure build-up time (Δt)
In this comparison, the single-pump pressure testing system reaches the target test pressure in less time than the multi-stage multi-pump architecture. This is understandable from a design perspective: a large single pump can build up pressure with high power density across a continuous characteristic map.
The multi-stage multi-pump solution, on the other hand, takes a different approach: The pressure is built up in defined stages, with each pump operating exclusively in its designated pressure range. This results in a systematically graded pressure ramp.
For operators, this means:
- clear trade-off between cycle time and connected load optimization
- defined, segmented pressure control across the individual stages
- high reproducibility of the test profile
Especially in applications with a focus on grid connection, energy efficiency, or system losses, the architectural decision can be made deliberately in favor of the multi-pump solution – even if the pure pressure build-up time is longer.
2️. Pressure loss (Δp loss):
A comparison of pressure build-up also reveals a difference in system-related pressure loss.
The multi-pump architecture enables more precise pressure control within the individual stages. This reduces the necessary “overpressure” of the pressure level.
- Minimizes hydraulic losses.
- Reduces system load.
- Improves control quality.
A lower p-loss not only has an impact on energy consumption, but also increases process stability, especially with high volumes and long holding phases.
Grafik1
Comparison of pressure build-up in a high-volume pressure testing system with a single pump and a staged multi-pump architecture: The staged activation of the pumps enables controlled pressure increase in defined stages (207 / 414 / 690 bar) with optimized power requirements.
Application Example: Implemented Multi-Pump Pressure Testing System
The following images show the implemented KAMAT multi-stage pressure testing system used for the verified comparison presented above. The system integrates staged high-flow and high-pressure pump units combined with a dedicated valve station for controlled pressure transitions.
More than Efficiency: What Connected Load Means for Planning and Operation
1. Grid connection and infrastructure
Transformers, switchgear, and feeders are dimensioned for the maximum connected load. A reduced connected load can:
- Lower investment costs
- Reduce grid connection requirements
- Create reserves for future expansions
This is a decisive factor, especially for energy-intensive locations.
2. Efficiency advantages at frequent operating points
High-volume pressure testing systems spend most of the test cycle in the filling and ramp range and not at the maximum final pressure.
The multi-pump logic ensures that the pumps run close to their optimum efficiency at these frequent operating points.
3. Redundancy and availability
Multiple pumps offer a certain degree of redundancy.
If one pump fails, the pressure testing system does not necessarily have to shut down. Depending on the process requirements, it can continue to operate in a reduced operating mode.
Trade-offs: What to Consider with Multi-Pump Pressure Testing Systems
As with any system decision, there are considerations to be made with multi-pump architecture:
- Larger footprint
- Higher investment costs
- More variants in spare parts management.
In practice, it is an engineering trade-off: more system intelligence (stage switching, valve station, control) versus potentially better efficiency, lower connected load, and higher availability.
Takeaways for Operators of Pressure Testing Systems
- A single pump is not automatically optimal if the volume is large and the pressure profile is dynamic.
- Staged multi-pump architectures, on the other hand, can significantly reduce the connected load.
- The technical key here is clean pressure staging in combination with a suitable valve station.
- Redundancy and better partial load efficiency are real system advantages, but footprint and CAPEX must be taken into account.
- Not only maximum pressure and maximum flow rate are decisive, but also the actual test profile of the pressure testing system.
Architecture Check for Your Pressure Testing System
If you are designing or modernizing a high-volume pressure testing system, it is worth carrying out a targeted architecture check.
- Pressure stages
- Cycle profile
- Connected load
- Valve concept
Often, the potential for optimization lies not in the individual components, but in the system architecture.
Contact us to receive a technical analysis of the architecture of your pressure testing system. This analysis is data-based, application-oriented, and individually tailored to your process requirements.
