• Integrated air vent screw for time-critical applications.
• Variable fixing options for surface or wall mounting.
• Flange connection to CETOP with special bore holes for several hole patterns.
• Robust and long-term stable design for demanding hydraulics.
• Two switching outputs with selectable diagnostic function.

Flexible mounting on hydraulic applications
The electronic pressure sensors of the PY700x series were specially designed for fast mounting according to requirements in hydraulic applications. If hole patterns of “hydraulic series connections” are to be used directly for the mounting of ifm pressure sensors, the sensor can be mounted vertically to the surface using the flange connection to CETOP. The connection to the pressure medium is made using four screws and an inserted O-ring.
As an alternative, the sensor can also be mounted parallel to the surface (wall mounting). Additional pressure connections to the measuring cell (1 x G 1/4, 2 x M6) are available for the connection of the pressure pipe independent of the fixing options. The M6 screw is also used as a venting option for a bubble-free hydraulic system.

Benefits of flange mounting
Using the fixing holes in the process connection the sensor can be directly mounted on a DIN rail or other panel in any position without any clamps. In addition to the flange connection, a G 1/4 I (bottom) and two M6 internal threads are available for the pressure connection on different levels of the process connection. For this flange mounting the slanted display is automatically frontlooking and can be read easily from all sides. Alignment of the sensor is not necessary. This type of mounting is very robust, easy and quick to mount – time is money!

• Increased repeatability across the measuring range.
• Simplified setting mode for quick set-up.
• Variable process connection using adapters.
• Reliable monitoring of gaseous and liquid media.
• Electronic locking of the setting values.

Simple, fast and flexible mounting.
The flow sensors of the SI5 series can be integrated into almost every application by means of a wide selection of process adapters. The robust stainless steel housing provides high reliability even in cases of harsh environmental conditions.The unit is unaffected by the orientation of the sensing face with respect to the direction of flow, providing increased flexibility of installation.

Easy handling and high functionality
Adjustment to the flow and setting of the switch points are carried out using pushbuttons. Current flow and switch point are indicated with the local multi-coloured LEDs.
Electronic locking of the settings and factory reset of the parameters provide additional safety.

• Breaking Pressure:
  

  The minimum pressure required to produce flow through a valve.

• Duty Cycle:
  

  100% duty cycle is defined as continuous operation without any damage occurring. For intermittent duty cycle (<100%), alternate energized and de-energized state at regular intervals to allow the valve to completely cool down to room temperature.

  F = active concentration / total concentration

• Flow Patterns:
  

  A diagram showing how flow can be directed using a particular valve. (See the “Flow Patterns” box below for further explanation.)

• Normally Closed:
  

  Valve stays closed in de-energized state; opens when energized.

• Normally Open:
  

  Valve stays open in de-energized state; closes when energized.

• Pressure Differential or Pressure Drop:
  

  The difference between the inlet and the outlet pressure through a valve. The outlet pressure is lower than the inlet pressure due to the restriction caused by the valve.

• Three-Way Valve:
  

  Has three ports. Depending on the particular valve, all three ports may be open, two ports may be open, or all ports may be closed.

• Two-Way Valve:
  

  Has a single inlet port and a single outlet port.

Selecting your Valve

1. Choose a valve type depending on your application. Our manual valve selection includes ball, check, diaphragm, elliptic, metering, needle, pinch, plug, pressure relief, and stopcock valves. Our actuated valve selection includes electrically actuated ball, elliptic, pinch, proportioning, and general-purpose solenoid valves.
2. Consider your fluid type (liquid or gas) and its characteristics to determine compatible valve materials. Teflon withstands many harsh or corrosive chemicals. For safety reasons, always use metal valves for pressurized gases.
3. Determine the temperature, pressure, and flow rate under which your valve will be operating. In general, metal valves withstand higher temperatures and pressures than plastic valves.
4. For solenoid valves, consider response time and length of time valve will be energized. Continuous (100%) duty solenoid valves are best for frequent on/off cycling. Choose normally closed or normally open depending on the state the valve will be in most often.
5. Consider your maintenance requirements. Ball valves resist plugging and are easiest to service.

Encord Sdn Bhd
11A, Jalan USJ 1/31, 47600 USJ 1, Subang Jaya, Selangor Darul Ehsan, Malaysia.

Tel : 603-80240919
Fax : 603-80240943
Email : enquiry@encord.com.my

Website: www.encord.com.my

In 2- to 30-inch bore sizes, 150 to 1500 Class, models employ patented redundant sealing technology: a primary seal and a secondary seal on each side of the trunnion supported ball. There is no pressure drop through the full opening valve plus lower automation costs are lower since it is a quarter-turn valve. These ball valves are for refined products pipelines, pig launchers/receivers, manifolds, or storage and injection wells.

Quarter-Turn Plug Valves
Weco ULT and DR plug valves are premium, quarter-turn valves designed for a wide range of standard and sour gas drilling, production and well-servicing applications. These rugged valves are offered in single- and dual-body designs in pressures to 20,000 psi. They range in size from 1 to 4 inches and come with threaded, Weco wing union, flanged ends, or combinations thereof.

When the valve is closed, the dual segment seal provides the sealing reliability of redundant sealing members on the downstream side of the valve. In 3-inch and larger sizes, the ULT plug valve also employs a two-piece plug and stem design.

Valve and Actuator Package
The TRIAC F91 valve/actuator package from A-T Controls is suitable for oil field, refinery, chemical processing, and other corrosive and caustic environments. The F91 stainless-steel flanged ball valves feature rugged construction, solid unibody and patented pyramidal stem packing, while regularport design minimizes cost and reduces operating torque. To save installation time and work, the valves feature a patented directmount actuator pad and can be ordered pre-assembled with robust, weatherproof WE electric actuator. The ANSIclass 150 valves are available in sizes from 0.5 to 6.0 inches.

Explosion-Proof Solenoid Valve
The new high-flow high-speed EExd Namur Series solenoid valves from Alcon are designed for use in hazardous area/extreme environment applications. Offering universal 5/2 or 3/2 operations in offshore, processing and chemical industries, the series is suitable for piloting single or double actuators on Namur solenoid valves.

An explosion-proof, submersible, watertight and dust-tight aluminium body for indoor or outdoor use, along with Nitrile seals, ensures reliable operation while meeting requirements for a wide range of environments.

These valves are designed for use with actuators controlling butterfly and ball valve systems in hazardous areas found in offshore, paper, recycling, food processing and chemical industries.

Seat Control Valve
Flowserve Corp. announces the Worcester CPT characterized seat control valve. The CPT series ball valve is engineered as a control valve and provides reliable operation and precise valve positioning in the most critical throttling conditions. These valves offer many customizable features that enable them to be used for some of the processing industries’ highestprecision applications.

The valves can be used in systems that control steam pressure or pH levels, operate in low-temperature cryogenic conditions or up to 1000° F (538° C), and meet EPA and OSHA specifications for containing toxic chemicals. Widely used in the oil and gas industry, the CPT has been approved by Factory Mutual for fuel gas safety shutoff service and flow control.

Metal-Seated Ball Valve
Marvin Valve’s MS3000 Series is a heavy-duty, metal-seated ball valve engineered for high pressure and temperature applications with an extended bonnet standard for pipe insulation and enhanced packing. The
MS3000 Series Standard or Full Port Ball Valve is a hard (metal or carbon-seated) valve designed for ease of maintenance with double body seals and enhanced stem packing.

The metal seats are identical upstream and downstream and can be interchanged during routine maintenance, thereby extending the effective life. Designed for applications with pressures to 990 psi (69 bar) and temperatures to 1000° F (538° C), this ball valve is ideal for condensate, steam or gas service.

Valve Controllers
Topworx has recently added a new member to its DXP range of valve controllers. This unit is ideal for the oil and gas industry and other applications that require precise position feedback. The Valvetop DXP with 4-20 mA analog feedback offers an innovative design that is unique to the industry.

The single pushbutton autocalibration feature eliminates zero/span interaction and reduces set-up time by 95%. Reverse directions are automatically accounted for during the calibration process, because it can be calibrated in both actuator/valve rotational directions without adjusting the feedback device position. Simply apply power to the unit, and press the autocalibration button.

Safety Chainwheel
The Babbitt Safety Hammer-Blow Chainwheel allows plant personnel to operate out-of-reach high-pressure valves easily from the floor by the simple pull of a chain without having to climb ladders. This product’s configuration provides a secondary attachment device that prevents the possible danger of a falling hand wheel to which a Babbitt Safety Hammer-Blow unit is attached. With this device, the chainwheel and handwheel are suspended at a safe overhead distance until replacement or reattachment.

These ductile-iron safety chainwheels fit hand-wheel rim diameters from 6 to 36 inches and are engineered to deliver long-term reliability in refining, processing and petrochemical applications. Galvanized, rust-proof, stainless-steel, spark-resistant, brass lock-link chain and Master Links are available.

Series 3000 XPIS Gas Detector
Honeywell Analytics introduces the Series 3000 XPIS gas detector for industrial applications. This robust gas detector utilizes existing two-wire systems to monitor for toxic and oxygen gas hazards in potentially flammable environments.

The device’s intrinsic safety (IS) and explosion-proof hazardous area approval allows the detectors to be wired alongside other field wiring without IS certification. This removes the need for cable segregation as required by IS-certified detectors, making the device both cost-effective and versatile. Operating on a standard 2-wire 4-20mA loop that makes it suitable for new and retrofit applications, the Series 3000 serves a variety of demanding industrial environments: exploration and drilling platforms, production platforms, onshore oil and gas terminals, refineries and chemical plants, power plants, wastewater facilities, utilities and others.

Alarm Analysis Tool
Emerson Process Management has introduced an Alarm Analysis tool designed for its Ovation expert control system. The system is a component of the company’s PlantWeb digital architecture, which delivers process and equipment diagnostics data over digital buses to improve plant operations and streamline maintenance activities. The Alarm Analysis package examines alarm data collected by the Ovation historian,
providing the user with information necessary to minimize unnecessary alarms. This, in turn, enables plant operators to more effectively address real, high-priority issues and focus on actionable items.

This tool offers various statistical analysis functions, including operator response analysis and plant upset analysis, as well as auto-correlation analysis, which considers the causal relationship between alarms, providing additional valuable insight for optimizing the generation and reporting of alarms.

Curved Bill Check Valve
The Curved Bill Tideflex Check Valve from Red Valve Co. is designed to enhance sealing, especially in lowlying areas with little backpressure. The valve is constructed entirely of rubber, making it virtually immune to rust, corrosion and weathering. The curved bill offers increased flexibility to better seal around entrapped debris, and the headloss of the valve remains exceptionally low. Applications include highway runoff, flood control CSO/SSO systems, site drainage, stormwater discharge, sewer systems, coastal discharges, odor control or any application requiring backflow prevention. The valve is available in sizes to 96 inches.

Diaphragm Valve and Control System
The coupling of Burkert’s Type 2031 Diaphragm Valve (1/2- to 4-inch process connections) and Type 8630 TOP Control System provides chemical equipment professionals a variety of intelligent on/off, positioning and proportional control options.

The Type 2031 is designed to accommodate polluted, dirty, abrasive and high-viscosity fluids. Featuring a two-way 316L stainlesssteel body—permitting higher flow rates than those achieved via conventional diaphragm valves—this maintenance-free valve is a suitable alternative to ball valves. The self-draining Type 2031 is corrosion-resistant and built for long service life.

The Type 8630 TOP Control System—the actuator-mounted PID controller or positioner for the company’s line of diaphragm and globe-style valves—features the Process Tune function for optimal control of the 2031 valve. This system, a self-calibrating digital positioning unit, provides on/off and continuous functionality, and also offers self-PID tuning. This allows optimized PID values to be automatically set to control a process, and the set point modulator prevents the loop from becoming unstable and causing system damage.

Electronic Product Configurator
ASCO has released its new electronic Redundant Control System (RCS) series product configurator. From the convenience of a computer, users can build a catalog number of an RCS Rev. C unit. They will also be able to download top level drawings, wiring drawings, SIL information, an O&M guide, and the RCS catalog.

The product configurator is available through the ASCO public site at www.ascovalve.com/RCSConfigurator. The configurator will not only allow the user to build a valid construction, it will also disallow all invalid combinations of features.

Valves for Transformer Oil Applications
Unifin offers a line of heavy-duty transformer oil valves, manufactured under the company’s Cardinal brand. Cardinal valves are specifically designed to meet the demanding requirements of transformer oil applications. To perform reliably under extreme operating conditions, these valves are rated for temperatures ranging from –40º F (–40º C) to 212º F (100º C). All parts are made from non-corrosive or a suitably protected material to withstand outdoor exposure on external surfaces and hot transformer oil on internal surfaces.

These valves are robust in design, so that over-tightening or minor abuse encountered in handling or during factory/field installation will not result in valve malfunction.

Fluoropolymer Diaphragm Valve
A new fluoropolymer diaphragm valve from the Partek operation of Parker Hannifin—the 20 Series—features a flow path and valve seat area that optimizes fluid flow dynamics, for minimal pressure drop and enhanced flow rates, and resistance to aggressive media. As a result, this valve offers a life of more than a million cycles in slurry applications, a greater than 50% improvement over Partek’s standard DI water/chemical valve technology.

Compliant with the SEMI-F57-0301 standard for polymer components, the new valve has a body machined from ultra-high purity PTFE for superior chemical resistance, and a one-piece, precision-machined diaphragm. It is available in three orifice sizes of 1⁄4, 1⁄2 and 1 inch, with port sizes ranging from 1⁄4 to 11⁄4 inches.

FOCUS: COMMERCIAL CONSTRUCTION

Zone Valves
Dwyer’s Series ZV2 and 3ZV2 Zone Valves are made for use with temperature controllers and thermostats to control temperature in HVAC systems. The valves control the flow of hot and cold water in the HVAC system thereby controlling temperature. Units come in two-way and three-way constructions and incorporate a bi-directional motor. They feature an easy push-button removable actuator design for ease of installation.

Supplied in ½, ¾, 1 and 1¼-inch sizes, valves are for use with supply voltages of 120, 24 or 230 Vac. Inputs are floating or modulating with 4-20 mA or 0-10 Vdc.

Differential Bypass Valve
A new Differential Bypass (DB) Valve designed to control excess flow in hydronic systems has been introduced by ITT Bell & Gossett. When there is a reduction in demand, the valve acts as a bypass while ensuring adequate flow to the remaining open circuits. Designed to be used in systems where heating loads may be excluded from the circuit as zone valves close, the differential bypass valve also helps reduce velocity noise caused by excess flow through the circuits while maintaining the pump head at a constant valve.

Developed for hydronic systems utilizing zone valves, the new valve offers the following features: a ¾-inch connection, all-brass body with non-ferrous internals; and a horizontal or vertical installation. Its maximum working pressure is 150 psig and can operate at up to 230° F (110° C).

Rigid Coupling
Victaulic has introduced the Style W89 AGS Rigid Coupling for use exclusively with stainless-steel pipe
Schedule S10 or higher. Developed for use with HVAC and industrial pipe installation to provide an inflexible joint, the coupling greatly reduces linear and angular movement through the use of wedge-shaped coupling housing keys that fully engage the grooves to provide rigidity on valve connections and other points where inflexibility is necessary.

Available in sizes from 14 to 24 inches (350 to 600 mm), these couplings are provided with plated bolts and nuts and FlushSeal gasket Grade “E” EPDM for multiple uses. Grade “T” nitrile and Grade “L” silicone are also available. Offered in standard galvanized steel or painted upon request, the couplings are suitable for use on stainless-steel piping where the corrosion-resistant properties of stainless steel are not required for the external environment.

Pressure Transducer
Setra Systems, Inc. announces the Model 209 pressure transducer. Rated for a variety of cost-sensitive applications, this transducer is made for use in HVAC applications, as well as for fuel cell development, OEM and industrial applications. It is compatible with a number of liquids and gases and contains no seals or “O” rings that could cause leakage. The weather-resistant transducer offers a small footprint (1.62-inch diameter x 2.24 inches, end to end) and is lightweight (3.5 oz). It has a stainless steel/Valox housing, stainless-steel wetted parts, choice of cable, or optional Hirschmann or Packard termination.

If you fully understand the cause, effect and prevention of cavitation as related to the process and the hardware, feel free to move on to another article. However, if you are new to the industry or don’t have a strong understanding of cavitation, read on.

Definition
Cavitation in a pipe occurs only with liquids, since by definition cavitation is the result of a liquid temporarily being converted to a vapor state followed soon after by a return to the liquid state. But if we have a pipe with liquid flowing through it and the liquid is under pressure, how and when does the liquid change itself to a vapor and then back again to a liquid? And why is this a problem?

How and When
Figure 1 demonstrates the velocity and pressure within a pipeline when the flowing media, liquid in our example, flows through a restriction. Obviously, the same amount of liquid is flowing through all portions of the piping. The smaller flow area of the restriction requires that the media flows at a much higher rate when passing through the restriction. Likewise, the media flows at a faster than normal speed as it approaches and as it leaves the restriction.

A few hundred years ago, Daniel Bernoulli pointed out that, ignoring friction, the amount of energy within a flow stream is the same at all points in a pipe and is the total of the energy due to velocity + pressure + elevation. If we consider a horizontal pipeline, then for energy to remain the same at all points in the piping when velocity increases, the pressure portion of the energy equation must be less. Summation: When the velocity in a pipe increases, the pressure decreases, sometimes to very low levels.

Liquids
If we heat water above the boiling point, it will turn to steam, i.e., the vapor form of water. The temperature at which water boils decreases as the pressure on the water decreases. At sea level it requires a higher temperature to boil water than it does in the mountains. If a mountain is high enough, water would boil at room temperature, i.e., we can boil water at any temperature by lowering the pressure to below the vapor pressure of the liquid at that temperature.

In a pipe, if the flowing velocity is great enough, the pressure within the liquid may fall to below the vapor pressure of the liquid. If this occurs, the liquid will boil at this location and turn to vapor.

Restrictions and Cavitation
Figure 2 portrays the velocity and pressure values as a liquid flows through a restriction. Note that at the smaller sectional area, the velocity increases and the pressure decreases. In the first graph, the pressure does not decrease to below the liquid’s vapor pressure; therefore it remains as a liquid at all points in the flow stream. There is a lower downstream pressure caused by energy losses caused by the restriction.

This is pressure drop. The lower graph shows what would occur if the velocity were to be great enough to cause the liquid pressure to fall below its vapor pressure value. At the point where this first occurs, some of the liquid converts to vapor and this conversion process will continue as long as the pressure remains below the vapor pressure of the liquid. However, some short distance downstream of the restriction, the flow area increases and the velocity returns to normal, raising the liquid’s pressure to above the vapor pressure. When this “pressure recovery” occurs, the media returns to a liquid state. The vapor is said to implode back to a liquid – i.e., cavitation.

Why Should We Care?
First, if cavitation occurs, the flow volumes no longer act in accordance with established flow sizing equations, thus rendering inaccurate the data upon which the valve and piping sizes were selected.

Second, cavitation is accompanied by considerable noise levels. Described accurately as sounding like heavy gravel passing through the pipe, cavitation can create noise levels above those acceptable for nearby personnel.

Third, cavitation is accompanied by often severe damage to the valve and downstream piping. The implosion from vapor to liquid removes surface particles from contacted materials, eventually destroying the subject component.

Therefore, we want not only to understand what cavitation is, but what we might do to prevent its occurrence.

If the Restriction is a Valve
Figure 3 portrays the effect on velocity and pressure that might be expected when a valve is controlling flow.

As a liquid flows through the valve, the flow area is less in the valve than in the open pipe and the flowing velocity in these areas is higher than in the open pipe. Additionally, the valve may cause a distortion of the flow stream such that lesser and greater flow volumes occur across the open areas.

Shown for example and discussion is a butterfly valve and a globe valve. Each acts as a variable restriction to the flowing media but each has differing affects on the flow stream and the likelihood of whether cavitation may occur.

Butterfly valves with their relatively straight through flow path, allow very high velocities to occur within and downstream of the valve. Globe valves have a rather torturous flow path, thus the internal flowing velocities are less than in a butterfly valve, given the same eventual pressure drop. Is one valve type more likely than another to create a situation where cavitation occurs? Globe type valves are often referred to as “high recovery” valves, whereas butterfly valves would be said to be “low recovery” valves. What does this mean, and how does it relate to the onset of cavitation?

Earlier in this article it was stated that the pressure “recovers” as the velocity slows downstream of a restriction. The same applies when a valve is employed as the restriction. Internal to the valve there is higher velocity than there is both upstream and downstream.

When the velocity increases internal to the valve, the pressure decreases. Downstream, the velocity slows and the pressure increases, or recovers, from the lower values internal to the valve.

With its more torturous flow path, a globe valve creates an equivalent pressure drop to that of a high butterfly valve but with lower velocities within the valve. Therefore, given the same pressure drop, the pressures internal to the globe valve will not be reduced to as low of a level as they would be in a butterfly valve. Since there is a smaller difference between the internal pressures of a globe valve and the downstream pressure, the globe valve is described as a low recovery valve. Logically, butterfly valves are described as high recovery valves.

Given identical differences between upstream and downstream pressures (pressure drop) there will be lower pressures internal to a butterfly valve than in a globe valve, although again, each causes the same pressure drop.

Figure 3 shows three situations. One is where the internal pressure of a high recovery and a low recovery valve is equal. The downstream pressure will be greater, by definition, for a high recovery valve.

The second situation shown in Figure 3 shows that while the downstream pressure, and pressure drop, may be identical with either a high or low recovery valve, the internal pressure within the high recovery valve will fall to a lower value that it does within the low recovery valve, and may fall below that of the vapor pressure of the liquid. Thus one valve type might experience cavitation while another, though controlling the same pressure drop, may not experience cavitation.

The third situation shows that a high recovery valve may induce cavitation even though the pressure drop it creates is less than the pressure drop caused by a low recovery valve.

If using a valve to cause a pressure drop (as opposed to control of flow volumes), it is safe to say that a low recovery valve will resist causing cavitation more so than a high recovery type. Of course, all valves can cause cavitation and to a differing degree at different travel positions. To predict if a valve will experience cavitation, certain valve manufacturers have performed extensive testing and can be relied upon to provide prediction and prevention information to users.

Can We Design to Reduce Cavitation?
Absolutely. With the information available from your valve supplier, it is possible to select an optimum valve type. Occasionally, it may be possible in a pressure control application to fit two or more high recovery valves in tandem within the piping, taking an equal fraction of the drop across each valve. In addition, some valve manufacturers have developed extremely effective “trim” or valve internals that combat both the onset and effect of cavitation. Again, look to your supplier for assistance.

ED HOLTGRAVER is CEO of QTRCO, Inc. (www.qtrco.com), located in Tomball, TX. Reach him at 281-516-0277.

The Pressure Relief Valve
The pressure relief valve is designed to provide protection from over-pressure in steam, gas, air and liquid lines. The valve “lets off steam” when safe pressures are exceeded, then closed again when pressure drops to a preset level.