Masoneilan 35002 DVD Camflex II Low Noise Differential Velocity Trim Valve

Overview

The Masoneilan 35002 DVD is the low noise configuration of the Baker Hughes Camflex II rotary control valve, fitted with the patented Differential Velocity Device, or DVD, trim. It is intended for compressible fluids such as air, gas and steam where the aerodynamic noise radiated by the throttling process becomes a problem for operators or for plant noise limits. Baker Hughes states that the DVD provides up to 18 dBA of noise attenuation, and it is available in 1 to 12 inch (DN 25 to 300) valve sizes in ASME Class 150 through 600.

In Oman and the GCC, Seven Star LLC proudly supplies the Masoneilan 35002 DVD to power, gas and process facilities in the Sultanate of Oman and across the GCC. Our valve team in Muscat checks the process data, noise requirement and pipe size with you, and confirms that the reduced Cv of the DVD trim suits the duty before an RFQ is issued.

Differential Velocity Principle

Noise from a throttling gas valve, which the Masoneilan 35002 DVD is designed to reduce, is carried by the high velocity jet leaving the restriction and radiated through the downstream pipe wall. The Masoneilan 35002 DVD borrows a concept from turbo-fan jet engines. A perforated plate is clamped into the valve body at the valve outlet. Its outer ring of holes has a larger diameter than the inner holes, so the flow is split into a high velocity core and a lower velocity annular envelope around the perimeter. The slower outer stream acts as a buffer that reduces the transmission of noise from the faster inner stream, which is why the brochure speaks of valve outlet flow stream conditioning that lowers the pipe wall noise level.

Baker Hughes describes the construction as simple, efficient and easy to retrofit. The trade-off is flow capacity. The DVD plate is an additional restriction, so the rated Cv of the Masoneilan 35002 DVD is only about 34 to 39 percent of the full-area Camflex Cv in every size, and Baker Hughes states that the DVD must be used with the 0.6 factor trim and with flow to open only. The characteristic is linear and the Cv ratio is above 50:1, compared with more than 100:1 for the standard trim.

Engineering Design of the Masoneilan 35002 DVD

In the Camflex II numbering system the DVD is selected through the trim type digit: trim type 3 is a metal seat with differential velocity trim and trim type 4 is a soft seat with differential velocity trim, which the instruction manual identifies as model numbers 35x3x and 35x4x. The plate itself is listed in the materials tables as a DVD low noise plate in 316 stainless steel. Everything else on the Masoneilan 35002 DVD follows the Camflex II platform: a body with integral extension bonnet, the self-aligning eccentric plug, a splined shaft and a triple bearing system, with Model 35 diaphragm or 5S piston actuators as described in the technical specification.

Maintenance of the Masoneilan 35002 DVD is covered in the Baker Hughes instruction manual. The DVD is installed in the body and removed by turning it counter-clockwise with a dedicated DVD wrench that engages the retainer lugs; Baker Hughes supplies wrenches for the 1 to 12 inch sizes and recommends them because specific tightening torques must be achieved to clamp the plate correctly. The manual lists reassembly torques from 74 lb.ft (100 N.m) for a 1 inch valve, through 363 lb.ft (490 N.m) for 4 inch and 780 lb.ft (1,050 N.m) for 6 inch, up to 2,250 lb.ft (3,050 N.m) for a 12 inch valve.

Key Features

The following points describe what the Masoneilan 35002 DVD adds to the standard Camflex II:

• Patented Differential Velocity Device splits compressible flow into a high velocity core and a low velocity envelope for up to 18 dBA noise attenuation.
• The device is a single clamped plate in the body, so construction is simple and the option is easy to retrofit.
• It is available in 1 to 12 inch sizes in ASME Class 150, 300 and 600 with metal seat or soft seat versions.
• Rated Cv runs from 5.0 for the 1 inch valve to 684 for the 12 inch valve, with a linear characteristic.
• The DVD is designed for flow to open and is used with the 0.6 factor reduced capacity trim.
• The plate is made of 316 stainless steel and is removed with a dedicated wrench for inspection or cleaning.
• The standard Camflex II features remain, including the extended bonnet, hardened trim and Class IV or Class VI shut-off.
• The Masoneilan SVI II AP digital positioner can be mounted directly on the actuator of the Masoneilan 35002 DVD.

Industrial Applications

The Masoneilan 35002 DVD is suited to typical gas and steam pressure reduction and control where an acoustic limit applies: fuel gas conditioning at power stations, compressed air and nitrogen distribution, vent and blowdown lines, and steam header letdown in refineries and desalination plants. In dense industrial zones such as Sohar and Salalah, where equipment is often installed close to walkways and control rooms, a valve that lowers pipe wall noise without a separate silencer is attractive because it keeps the installation compact.

Seven Star LLC supplies the Masoneilan 35002 DVD to EPC contractors, plant operators and maintenance organizations throughout Oman and the GCC. Where the Masoneilan 35002 DVD is not enough for larger noise reductions or severe pressure drops, we also supply multi-stage trims from other Masoneilan series, and the standard Masoneilan 35002 Series Camflex rotary control valve remains the choice when noise is not a concern. The Masoneilan SVI3 digital valve positioner and the Type 87/88 Camflex actuator diaphragm page cover positioning and a Camflex diaphragm spare.

Technical Specifications

The table below summarises the principal data of the Masoneilan 35002 DVD as published in the Baker Hughes Camflex II technical specification, brochure and instruction manual. Please consult the official documents for complete data.

Related Masoneilan low noise and Camflex products include the Masoneilan 49000 Series V-LOG low-noise valve and Masoneilan 35002 GR Globe Replacement Camflex.

Request a Quote for Masoneilan 35002 DVD

Please include the fluid, flow rate, inlet and outlet pressure and the allowable noise level in an RFQ for the Masoneilan 35002 DVD, so that sizing can confirm that the DVD trim is the right choice. Our Muscat instrumentation division checks regional availability, and the Baker Hughes technical specification and instruction manual can be downloaded from this page. In Oman and the GCC, Seven Star LLC supports each valve with manufacturer documentation and local support.