What do the terms Standby, Duty and Assist mean?

Within a packaged booster set each individual pump can be assigned a different role to perform different tasks, such as increasing performance or improving reliability as required.

A correctly specified booster pump set should take into consideration the requirements in peak times as well as the average demands. For example, if the set is supplying an apartment block with showers then the peak load will be in the mornings, at this point the DUTY and STANDBY pump will be required to operate to the demands. During the rest of the day, the DUTY pump should be able to supply the majority of the requirements with perhaps only occasional assistance.

Ideally in booster pumps like the PUK VARI COM each pump will have an assigned role of its own. In smaller pumps like the PUK VARI TWIN and PUK VARI TANK the role might be shared such as ASSIST/STANDBY. This means the second pump can assist the DUTY pump when required or even replace it if needed. When roles are shared the system is compromised as a pump can only perform one function at a time, so keeping roles separated is desirable when possible.

A well-designed booster pump should be configured to swap the assigned roles (DUTY/ASSIST/STANDBY) across the pumps within a set in order to share the usage across the system. This is usually performed at pre-set time intervals such as every 24 hours.

The DUTY pump is the main pump within a system. It should is designed/specified to supply a system with the required flow and pressure for the majority of the time. If there are unusual demands the ASSIST pump will help.

• The DUTY pump that performs most of the work.
• A DUTY pump should be sized to cover the majority of the flow/pressure requirements.
• The role of DUTY pump should be swapped to another pump within the system to spread the wear and prolong the system life, this is usually done at a pre-set interval.

The ASSIST pump is enabled when the DUTY pump cannot meet its requirements on its own. This pump will then add to the performance of the system. The performance of this pump should match the DUTY pump and should be considered in the initial requirements of the pump.

• The ASSIST pump only performs when the DUTY pump cannot meet the demands required.
• The ASSIST pump should not be designed to used often, if it is then the DUTY pump is not large enough.
• The role of ASSIST pump should be swapped to another pump within the system to spread the wear and prolong the system life, this is usually done at a pre-set interval.

The STANDBY pump is only used as a backup and is the same size as the other pump in the system. It is only used when a DUTY or ASSIST pump is taken out of line or is faulty/broken.

• Ony used to replace a ‘non-working’ pump within a set.
• The STANDBY pump is the same size as the other pumps within the set.
• The role of STANDBY pump should be swapped to another pump within the system to spread the wear and prolong the system life, this is usually done at a pre-set interval.