Plenty Mirrlees have extended the range and versatility of the C6000 series triple screw pump to offer more flow selections, higher pressure capability, more configurations and additional mounting options. The type 7 insert has been re-designed to form a pump in its own right, without the need for an additional casing, primarily for direct machine mounting and tank top versions. The type 7 insert retains dimensional interchangeability with its predecessors, the types 5 and 6 in respect of the critical dimensions for mounting in new and already installed C6000 series pump casings.
The type 7 offers a much improved and extended range yet retains all the interchangeability required for servicing the existing pump population.
Cast iron casings have been upgraded to Ductile iron (SG iron) to improve the reliability and integrity of these critical pressure containing components. This upgrade improves the acceptability of the product of oil industry installations.
Short lead (SL) screwsets have been introduced as an alternative pitch to the existing screwsets, known as normal lead (NL). This option effectively provides two alternative flow rates for each insert frame size, doubling the number of pumps available in the range. This shorter pitch screwset, with lower axial velocity and more sealing points along its length, provides a higher-pressure capability.
The short lead (SL) screwset pitch provides a flow displacement (flow before slip) 80% of the equivalent size normal lead (NL) version.
Within the C6000 series insert and pump the maximum pressure rating of the short lead (SL) screwset is increased by 20% over the equivalent normal lead (NL) version.
The section lift capability is increased with the short lead (SL) screwset. The pump requires less 'net inlet pressure' to operate than its equivalent normal lead (NL) version.
The type 7 insert has various suction end connection options which allows the insert to be used as a direct driven machine mounted pump (typically on large rotating machines as a direct driven lube oil pump) or as a lube system tank top mounted pump without any additional casing.
The insert can be pedestal or bracket mounted to form an economical horizontal pump where a ductile iron case is not deemed necessary for the environmental of operation.
Vertically mounted pumps with fabricated steel casings are an addition to the range.
WARNING: As with all positive displacement pumps a pressure relief valve should be provided as a safety device against a closed or blocked discharge. Due to the differing flow rates, viscosities and temperatures encountered for each pump, Plenty Mirrlees DOES NOT equip the C6000 series pump with an internal safety relief valve. A properly sized and rated pressure relief valve should ALWAYS be installed in the discharge line prior to any isolation valve.