Tuesday, January 27, 2015

Control Valve Application Checklist

Specifying of applying an industrial control valve? Here is a comprehensive checklist to help:

PROCESS CONSIDERATIONS:
Warren Control Valve
Control Valve
  1. What is the medium to be controlled. Is it a liquid, gas, or slurry?
  2. Is it corrosive, abrasive, explosive or clean single-phase medium?
  3. What is the upstream or inlet pressure. Don’t guess – use a gauge.
  4. What is the downstream pressure when valve is closed, and when flowing?
  5. Are the Vapor pressure, viscosity or specific gravity and critical properties known?
  6. What are the inlet and outlet pipe size(s) [ May be different ] and schedule?
  7. Normal, Minimal, and Startup conditions for flow, pressures and temperatures?
  8. What impact will even a small seat leakage create when shut off?
  9. What Class is required?
  10. Is the installation in an occupied area. Noise or other hazardous considerations?
  11. What is the “fail safe” orientation? In place, closed or open?
  12. If in a fail safe orientation, is a manual readjustment to be expected?
  13. What is the ANSI Pressure Class of the pipe flanges and valves in the loop?
  14. What has been the operational history in an existing application?
  15. What material is the existing piping made of. Is it considered compatible?
  16. Is there an existing valve in place and a face-to-face dimension to match?
  17. Where will the valve be located – elevation – within a piping nightmare?
  18. What maintenance – routine or preventative is normal and expected?
  19. What are preferences for Control Valve Actuation – pneumatic or electric? WHY?
  20. Is the customer going to actuate it himself and buy a “bare stem” valve?
  21. Is the stem boss compatible with his actuator stem. Double “D” or square?
  22. Is the calculated flow velocity below limits of 100 – 125 fps for saturated steam?
  23. Is the calculated flow velocity below limits of 5 fps for liquids?
  24. Is the calculated flow velocity below limits of 250 – 400 fps for gases?
"REAL WORLD" APPLICATIONS CONSIDERATIONS:
  1. Could moving vehicles damage the valve, in a specific installed location.
  2. Might seismic forces or fires present a danger to workers.
  3. What codes may be in effect? Body pressure Code, Leakage Criteria
  4. Might workers use the valve as a stepladder when conditions dictate?
  5. Is the application a “continuously modulating” or an on / off practice?
  6. Might the process be shutdown for nights or weekends?
  7. What might result when started back up after an extended shutdown?
  8. Use your imagination, anticipate the worst, and ask more questions – more, in this case, is always better.
  9. What range air set is available for actuator or positioner?
  10. Could it allow a higher than safe pressure?
  11. Where will the user store documentation for IO&M purposes?
  12. Is routine maintenance allowed or is an annual shutdown more typical?
  13. Could moving vehicles damage the valve, in a specific installed location?
  14. Might seismic forces or fires present a danger to workers?
  15. What codes may be in effect? Body pressure Code, Leakage Criteria?
  16. Might workers use the valve as a stepladder when conditions dictate?
  17. Is the application a “continuously modulating” or an on / off practice?
  18. Might the process be shutdown for nights or weekends?
  19. What might result when started back up after an extended shutdown?
  20. Use your imagination, anticipate the worst, and ask more questions – more, in this case, is always better.
  21. What range air set is available for actuator or positioner?
  22. Could it allow a higher than safe pressure?
  23. Where will the user store documentation for IO&M purposes?
  24. Is routine maintenance allowed or is an annual shutdown more typical?
PHYSICAL AND CONFIGURATION CONSIDERATIONS:
  1. Flowing media to be controlled. Steam, Liquid or Gas?
  2. Pressures upstream and downstream, therefore the differential.
  3. Two way – modulating, or on/off. Three way diverting or mixing?
  4. Is the material abrasive, explosive, or clean?
  5. Hot or Cold water chemically treated?
  6. What are inlet and outlet pipe sizes and schedules?
  7. Maximum, Normal and Startup conditions?
  8. Leakage allowed?
  9. Valve in occupied area?
  10. Previous usage history?
  11. Pipe material of construction?
  12. Actuation Pneumatic or Electric
  13. Maintenance allowed or anticipated?
  14. IO&M storage and accessibility?
  15. Control signal – PID compatibility?
  16. Mounting restrictions?
  17. How was valve “sized?”
Checklist courtesy of Warren Controls

Please consult with a application expert before selecting or installing a control valve.

Wednesday, January 21, 2015

Safety Relief Valve Basics

safety relief valve
Safety Relief Valve (Kunkle)
The safety relief valve is used to control or limit the buildup of pressure in a piping system, tank or vessel. Uncontrolled pressure can occur because of valve malfunction, process system upset, instrument failure, or fire.

In generally accepted practices, pressure build-up is relieved by allowing the fluid to flow from an alternate path in the piping system. A safety relief valve is engineered so that it opens at a predetermined pressure setpoint to protect vessel, piping or ancillary equipment equipment from being subjected to pressures that exceed their design limits.

When process pressure is exceeded, a safety relief valve becomes the “weak link”, and the valve opens to divert a portion of the fluid to another path. The diverted liquid, gas or liquid–gas mix is usually routed through a piping system to a process where it is safely contained or burned off via a flaring system. Once the liquid or gas is diverted, the pressure inside the vessel drops below the safety relief valves' re-seating pressure, and the valve closes.

Tuesday, January 20, 2015

Non-Hazardous Industrial Pressure and Temperature Switches

A quick reference to Custom Control Sensors (CCS) DualSnap non-hazardous pressure and temperature switches for industrial process control application.

Used in petrochemical, chemical, water treatment, pulp & paper, military, aerospace, commercial food processing, power generation, pipelines, bulk storage facilities and mining.

Tuesday, January 13, 2015

Cavitation in a Water Pump and Valve - Excellent Visual and Audible Demo...

Cavitation is the formation of gas bubbles in a flowing liquid when the pressure of the liquid drops below its vapor pressure. Sometimes a difficult concept to grasp, this video offers an excellent demonstration on what actually happens inside process piping, pumps and valves during this phenomena.


Sunday, January 4, 2015

Plastic Cooling Towers Offer Significant Advantages

Delta Cooling Tower
Delta Cooling Tower

CORROSION PROOF
Plastic cooling towers are made of a corrosion proof engineered plastic. The cooling tower shell will never rust, flake, chip, peel, or ever need painting or protective coatings applied.

Some industry experts are predicting that plastic towers may just be the future of the industry. Metal towers do not have the long-term corrosion protection advantages for outdoor usage.  The Galvanizing or other metal treatments only delay the corrosion of the underlying, often thin gauge sheet metal.

SEAMLESS CONSTRUCTION
Some manufacturers offer a totally seamless cooling tower.  The tower shell is rotationally molded of polyethylene plastic. One manufacturer, Delta Cooling Tower, offers the only large packaged cooling tower in the industry that has a “one Piece” shell, thereby eliminating the seams, panels, rivets, or hundreds of fasteners that potentially fail and compromise the performance or integrity of the product.

LIGHTER IN WEIGHT
Due to our materials of construction, plastic cooling towers can be 30% to 50% lighter in weight than steel towers of the same capacity. This is beneficial  on roof installations, light weight raised platforms, or at ground level installations by reducing the rigging / placement cost.

LONGER WARRANTIES
Plastic cooling towers typically offer longer warranties than their metallic cousins. A 20 year warranty isn't unusual for the structural shell of a plastic cooling tower.

LOWER MAINTENANCE
Plastic cooling towers are, by their very nature, lower maintenance than metallic.