incorrect . In addition , centrifugal pumps do not normally selfprime unless this type of design is specified early on in the process . If the fluid contains entrained gas , or has a low boiling point – common in some refrigerants or chemicals , a side channel pump which has a low NPSH may be the most effective way of tanker emptying .
In contrast , a positive displacement pump has a higher initial cost , but performance is guaranteed and unaffected by changes in viscosity , temperature or discharge losses . A positive displacement pump performance curve is actually a straight line meaning when viscosity increases so does performance . Unlike a centrifugal pump , positive displacement pump flow is proportional to RPM and doesn ’ t reduce with pressure .
• System and pump protection To ensure longevity and reliability , serious consideration needs to be given to system and pump protection . Steps that can be taken include incorporating antivibration mounts to prevent shock starts and stops from the units transferring to the connecting pipework .
In addition , integrated relief valves can be fitted to the pump for pump protection , along with
To ensure longevity and reliability , serious consideration needs to be given to system and pump protection .
pressure transducers or switches to stop pumps operating if discharge pressures exceed set limits .
Our diesel fuel unloading pump bespoke features
At North Ridge Pumps , we ’ re not tied to just one pump technology . Using our experience , we can specify the best pump for any application based on the lowest lifetime cost . We use our expertise to offer a bespoke solution - not something straight off the shelf .
For this specific diesel unloading pump application , we selected two NRBAL Rotary Vane pumps to be incorporated into the truck unloading skid supported by a range of tailor-made product features for this client .
Manual or automatic operation
The diesel unloading pump skid we specified can be set for both . With automatic operation it starts or stops according to inputs or set criteria being met . Whereas manual operation means that the operator takes control of all functions .
In addition , both pumps were mounted on a common baseplate with anti-vibration mounts , a set of pressure gauges , integrated strainers and a safety relief valve for pump protection .
Bespoke control panel
Control panels on skid-mounted pumps are often customised to meet the requirements of the system and the application . They are essentially the brains and act as an interface between the pump and any connected pipework , obtaining feedback from inputs or sensors and following a predetermined course of action .
For this project , we designed , manufactured and integrated a 15Kw DOL ( Direct Online ) bespoke panel with the following specification onto the truck unloading skid :
• Integrated flow meter totaliser giving remote monitoring with hard-wired contacts for pump running , pump fault and flow 4 to 20mA via a splitter
• Phase Failure relay and motor protection to prevent pumps from operating if a phase is down or supply is out of symmetry . Plus an indicating lamp on the door to warn if phase failure has occured
• Two sets of control gear consisting of protection breaker , contactor and overload all rated to 15kw
• A beacon with green and red indicators mounted on top of the panel with green for pump running , red for alarm
• Supply of safety relay and terminals for a Newson Gale Road Truck Recognition ( RTR ) truck grounding device .
• Low pressure switches in relay logic to stop pump after a timed period
Flow rate totaliser and indicator
This enabled the operator to verify that the pump set was working as required , and it provides accurate measurement of the amount of diesel being transferred into the tanks .
Pressure transducer / switch
This shows operators the pressure that the equipment is operating under , to ensure that there are no performance issues .
If you have any application requiring the transfer , circulation or injection of any kind of liquid of any viscosity and aren ’ t sure which pump to specify , speak to North Ridge Pumps to see how we can help .
For further information , please visit www . northridgepumps . com
Issue 66 PECM 75