Equipment Redundancy
Equipment Redundancy
(OP)
For my Compressed Air Plant I have used 3 X 50% Air Compressors as this has been specified by the ultimate Owner. Capacity of each Compressors is selected as 200 cu.m per hr.
My question is if required can I use the Compressors at 3 X 100%. What are the implications. What is the significance of 3 X 50% or 2 X 100%. Is their any relation to the design output of the equipment?
My question is if required can I use the Compressors at 3 X 100%. What are the implications. What is the significance of 3 X 50% or 2 X 100%. Is their any relation to the design output of the equipment?





RE: Equipment Redundancy
My first question would be can your distribution system handle the additional air flow to user or ursers? If the air is dried before it's used, can your air driers keep up with the additional flow?
RE: Equipment Redundancy
It follows that 3 x 100% = 3 machines, each with a capacity of Q, would imply one pump running, with 2 machines on standby. That would only be specified for an operation that required something like 99.995 reliability, where even if two pumps were not working, you would still be able to start #3 and operate at 100% capacity. Most operations would typically not need that reliability and could easily withstand operating for a short time at 50% Q, until a pump is repaired, but if you need almost perfect reliability at 100% capacity, 3 x 100% is what you would need to order.
"People will work for you with blood and sweat and tears if they work for what they believe in......" - Simon Sinek
RE: Equipment Redundancy
It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)
RE: Equipment Redundancy
Dear BigInch - your logic is well understood. As a generalized scenario if I have a short time demand, can I use the third unit at say 50% when the other two are being used at 100%. Is there a statutory regulation that the third unit should not be brought in service except under breakdown / maintenance condition of the one of the two operating units? I will design the distribution system to take the extar output.
Thanks TD2K / BigInch for your help. I find the forum really useful. Regards.
RE: Equipment Redundancy
RE: Equipment Redundancy
Three compressors running and equally sharing load at 83% of their individual design load should be possible. Whether running 3 compressors to make that 500 m3/h will be allowed by contract, we don't know. It depends on how your contract treats that 500 m3/h load. Is there a stated capacity of 500 m3/h that must be meet by running 2, and only 2, compressors in the contract, or is the 400 m3/h defined as the one and only maximum, or design, flowrate? Are there any other provisions in the contract that in any way require more than the 400 m3/h flowrate?
"People will work for you with blood and sweat and tears if they work for what they believe in......" - Simon Sinek
RE: Equipment Redundancy
Regards....
RE: Equipment Redundancy
"A complete compressed air plant shall be provided to meet all instrument and service
air requirements. The air compressors shall serve both instrument air and service air with priority given to instrument air and essential service air in cases of very low header air pressure. All compressors shall be of the same capacity. Normally, two (2) air compressors
shall be operated to meet the compressed air normal continuous demand for the
plant instrument air and service air system. The remaining air compressor unit shall
be on standby mode. The arrangement that determines the highest capacity of the
individual compressors shall prevail". Sizing of the Compressors is Contractor's responsibility. The values I quoted are just examples.
(@CaracasEC) The Compressors are electrical, direct driven, oil free, rotary type.
What I conclude from all the discussions that irrespective of the Plant type (a pump system, a compressor system or anything else); if 3 X 50% redundancy is specified - there is no harm technically to use the third unit and it will not be detrimental to the balance of the system if properly designed. Under normal circumstances the redundancy should not be breached. But extreme emrgencies if used should not be a matter of concern.
RE: Equipment Redundancy
"People will work for you with blood and sweat and tears if they work for what they believe in......" - Simon Sinek