Model C500 Plug Resistant Orifice

The C500SW diffuser is the socket weld version of CU Services LLC's family of high-pressure-drop diffusers. It can be used individually or as a multi-stage-orifice system of two or more units placed in series to eliminate the damage that is caused by control valve cavitation.

For example, two of the most difficult flow control problems in a power plant are the control of the Boiler Feed Pump recirculation and boiler feed pump warm-up systems. Another example is the boiler blowdown system.

These diffusers can be used for any flow-restriction orifice service.

Because of the high-pressure drops involved with these high temperature liquid streams, the fluid flashes and/or cavitates at the exit of the  control valve. This erodes both the control valve and the downstream piping. In addition the resulting pounding as the fluid implodes causes unacceptable noise and vibration of the piping. In some cases, the control valve, the downstream piping and the hangers must be replaced in a matter of months.

Assenbly Flanged	When multiple plates are used, each stage is sized to avoid cavitation.

CU Services LLC now offers a solution to these problems. It involves multi-stage orifice plates: The flow is controlled to specifications with the first C500SW diffuser. The energy is then dissipated in the next stages of C500SW diffusers. This greatly reduces or eliminates the cavitation and pipe vibration damage.

One of the most respected hydraulic laboratories in the country has validated the performance for our multistage diffuser design for the pump recirculation system for nuclear power plants.

The Control Valve should be located upstream of the break-down orifices. For on/off control situations, the high-drop control valve should take approximately 20-30% of the pressure drop and the diffusers take the rest of the drop. For modulating control situations, the high-drop control valve should take 60-70% of the pressure drop and the break-down orifices take the rest of the drop. This will greatly reduce the initial cost and the maintenance cost of the control valve.

The use of multiple-hole-orifices causes a shift of the frequency spectrum of the exiting fluid stream to higher frequencies resulting in a noise reduction in the order of 10dBa. The peak frequency scales inversely with the jet diameter ( f a 1/d). Thus, with multiple holes the resulting higher frequency greatly reduces the potential to excite the downstream piping, thus reducing damaging vibrations. A report describing this phenomena is available in the August 2001 issue of Hydrocarbon Processing magazine.

The increase in frequency of the exiting fluid stream is f2/f1 a v N where N is the number of holes. For example, for a plate with 24 holes, the peak frequency will be 4.9 times higher than the peak frequency of a single hole passing the same amount of fluid.

Another important benefit of a multi-hole diffuser is that the energy of the discharge jets is dissipated in a much shorter distance than the jet from a single orifice. This would prevent damage to nearby elbows, etc.

The Nuclear Regulatory Commission notice 98-45 has warned of flow induced vibration damage that can be caused by condensate flow in single-hole, single orifice let-down systems. View this report on the www.nrc.gov web site.

The NRC has also cautioned against using torturous path valves or devices because of a plugging potential view the Nuclear Regulatory Commission Report. Our diffusers are not torturous path devices. We design them to minimize the potential of plugging.

The C500SW body is fabricated from the highest quality of forged bar stock ASME-SA479-316SS. Pressure rating is the same as Sch 160 316 SS pipe.

Users of C500SW diffusers include Celanese Co. at Pampa, Texas; Pacific Gas & Elec at Carney's Point; Constellation Services at Panther Creek; KCPL at Hawthorne Station; Michigan I&C at U of Michigan; Zachary Construction at Jacksonville Northside; Kvaerner at Calpine Baytown; Jackson County RRF at Jackson, MI; Michigan I&C at Michigan Paperboard, Domino Sugar at Arabi Louisiana, Michigan I&C at Dearborn Generation Facility, Hawaiian Electric at Kahe Station, Lockwood Greene at West Phoenix CC5, Burns & McDonnell at Zeeland II CC.

CU Services LLC | 725 Parkview Cir. | Elk Grove Vlg, IL  60007
Phone: 847.439.2303

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