A contractor must decide between two different pump systems

A contractor must decide between two different pump systems to be installed in a new housing development .The option is to install a single 1000 litre per minute(lpm) system or two 500 lpm systems.If the two-pump system is used, one pump can carry most of the load in the event the other pump fails.Both the 500 lpm pumps have an MTTF of 800 hours when working together.Their individuval MTTF is 200 hrs.The 1000 lpm pump has a rated MTTF of 700 hrs.Which system is preferred on the basis of the sysytem MTTF? Which system has the best design life for the reliability of 0.80

Solution

AS GIVEN 1000 LITRE HAS 700 MTTF WHILE THE OTHER TWOO 500 LITRE HAVE 800 MTTF COMBINE BUT 200 MTTF ALONE

ON A PRACTICAL PURPOSE THE MTTF IS A LIFE OF THE PUMP

IF WE TAKE THE 1000 LITRE THEN THE MTTF IS 700 AND MOST PROBABLY IT WILL COVER ITS LIFE BUT IT DOES NOT FALL UNDER OUR CRITIRIA OF 0.80 RELIABILITY AS ITS RELIABILITY IS 0.70

N THE OTHER HAND IF WE CHOOSE TWO PUMP OG 500 LITRE AND MAKE SURE THAT NO OVERLOAD IS THERE ON THE SINGLE 500 LITRE PUMP THEN THE COMBINE MTTF OF BOTH WILL BE 800

WHICH GIVES US THE RELIABILITY OF 0.80

HENCE THE BEST OPTION IS TO GO WITH TWO 500 LITRE PUMPS