Placing a CRV® flow conditioner at the inlet to the manifold provides smooth inlet pressure, and eliminates cavitation, resulting in a more efficient running pump, generating less noise and vibration while increasing the pump throughput. This results in a lower cost, more efficient pump operation as well as lengthening the maintenance free operating life of the pump, reducing significant maintenance expense and very expensive downtime.

Top view of double-suction pump showing how plain elbow creates cavitation while a CRV® promotes an even fluid distribution.

Since all centrifugal pumps require well-developed inlet flow to meet their potential, a pump may not perform or be as reliable as expected due to a faulty suction piping layout such as a close-coupled elbow on the inlet flange.

When poorly developed flow enters the pump impeller, it strikes the vanes and is unable to follow the impeller passage. The liquid then separates from the vanes causing mechanical problems due to cavitation, vibration and performance problems due to turbulence and poor filling of the impeller. This results in premature seal, bearing and impeller failure, high maintenance costs, high power consumption, and less-than-specified head and/or flow.

In many instances, pump purchasers buy the least expensive pump that will deliver the specified flow and head within the NPSH available. Such a pump with high suction specific speed operating at 3,600 rpm or greater requires a well developed, uniform flow pattern at a narrow flow rate range since the impeller inlet eye and vanes are optimized to not create turbulence at design flow. This pump design feature is very susceptible to non-uniform inlet flow because when liquid velocity varies and does not meet the pump design assumption of a uniform velocity striking the impeller eye, flow separation results which causes cavitation and associated problems.

To have a well-developed flow pattern, pump manufacturer's manuals recommend about 10 diameters of straight pipe run upstream of the pump inlet flange. Unfortunately, piping designers and plant personnel must contend with space and equipment layout constraints and usually cannot comply with this recommendation. Instead, it is common to use an elbow close-coupled to the pump suction which creates a poorly developed flow pattern at the pump suction.

With a double-suction pump tied to a close-coupled elbow, flow distribution to the impeller is poor and causes reliability and performance shortfalls. The elbow divides the flow unevenly with more channeled to the outside of the elbow. Consequently, one side of the double-suction impeller receives more flow at a higher velocity and pressure while the starved side receives a highly turbulent and potentially damaging flow. This degrades overall pump performance (delivered head, flow and power consumption) and causes axial imbalance which shortens seal, bearing and impeller life.

By imparting a swirl to the flow entering the elbow, the CRV® enables the liquid to negotiate the turn and be evenly distributed to each side of the impeller. With the CRV®, flow and characteristics will approach factory rated pump test performance, cavitation and noise will diminish seal, bearing, and impeller life will improve.

The CRV® compensates for specification and installation constraints and attacks the root cause of poor pump performance due to faulty suction piping layout. With CRV® installation, pump performance and reliability will be maintained despite close-couple elbows on pump suctions, even when applied in high suction specific speed and double suction pumps.

Pump Cavitation Problems:	CRV® Benefits
Cavitation, Flow Separation, Vibration, Noise	Reduced maintenance intervals- less downtime & higher reliability
Frequent seal bearing or impeller replacement	Reduced cavitation, vibration, & noise
Non-uniform suction flow creating reduced flow	Increased flow and efficiency
Lack of space for proper pump installation	Reduced piping cost and space requirements

 

Adding a CRV® shows that the pumps performance can be improved significantly by solving the turbulence caused by the elbow.

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When the pump cavitates and forces a plant outage, a refinery could lose about $1 million a day in productivity.

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The key benefit, however, was reduced vibration, which eliminated a frequent repair cost of $5,000 on the shaft and bearings as well as an occasional sever-failure repair cost of $14,000 per occurrence.

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Our flow conditioners are custom made to specifically address each piping issue offering the greatest achievable flow correction.