vendor code reviews

 

Cv and “Cf” of a valve

 Critical Flow Factor, often referred to as “Cf” is a coefficient that defines how pressure will recover after it drops to its lowest point inside the control valve. This lowest point is also referred to as the vena contracta*.

All globe-style control valves have a Cf that stays consistent regardless of the trim position, unlike the Flow Coefficient (Cv).

Note: The Pressure Recovery Factor (FL) also refers to the Critical Flow Factor in some literature.

What is Cf Used For?

Cf is a factor needed in order to calculate Flow Coefficient (Cv) or Flow Rate for valve sizing purposes. 

What is Valve Flow Coefficient (Cv)?

Valve Flow Coefficient (Cv) is a valve’s capacity for a liquid or gas to flow through it.

It is technically defined as “the volume of water at 60°F (in US gallons) that will flow through a valve per minute with a pressure drop of 1 psi across the valve.”

As the stem opens, the Cv increases.

The maximum Cv for the 2-inch regulator is 47, while the maximum for the 3-inch regulator is 117.

CWE

 Cold Water Equivalent means the barrels of steam expressed in terms of an equivalent cold water volume with the cold water density being 62.4 pounds mass per cubic foot.

999.5521145351039 kg/m3

Convert to mass flworate and then use that to determine the volumetric flowrate at the temp and pressure u desire

Bubbler Panel

Bubbler System Process

The bubbler system works by forcing a gas (compressed air) 

at a near-constant flow rate out the bottom of an open 

tube (bubble/dip tube) submerged in liquid. The back pressure 

in this tube is measured. With the process liquid’s density known, 

the level can be calculated using the back pressure and 

density. A pressure transmitter converts the back pressure to 

provide a 4-20ma output to a controller, which calculates 

the liquid’s level.

As the liquid level increases, the head pressure on the bubble tube gets higher. This means more pressure is needed to maintain a constant flow rate to overcome the pressure of the fluid.

If the fluid level goes down, so does the head pressure on the bubble tube and the pressure required to maintain constant flow rate of air or gas.  

To minimize maintenance requirements, we can add a purge line to clear the bubble tube of debris and buildup. This can be a manual operation with the push of a button, or automated with a purge schedule and timer.

https://www.instrumentationtoolbox.com/2014/06/bubbler-tube-system-for-level.html?m=0

https://automationforum.co/troubleshooting-advantages-disadvantages-and-application-of-the-bubbler-type-level-measurement-system/

pump types

Types of pumps

https://www.ny-engineers.com/blog/main-types-of-pumps

Fig.1. Pump classification.1

SUB-TYPE	DESCRIPTION	EXAMPLES
Reciprocating Pump	Flow is established inside a cavity that expands and contracts, such as a piston. Water moves into the cavity during expansion, and is forced out during contraction, while the flow direction is controlled by using check valves.	Bladder Diaphragm Peristaltic Piston/plunger
Rotary Pump	This pump type uses a rotor that traps water in cavities, releasing it at the outlet. These cavities can be the spaces between gear teeth or screw threads, among other configurations. Some designs use more than one shaft, but the principle is the same: the rotor shape is designed to capture “pockets” of water and displace them in the intended direction.	Gear Screw Progressing cavity Rotary lobe Rotary vane

SUB-TYPE	DESCRIPTION	PERFORMANCE
Axial Flow Pump	Also known as a propeller pump, it produces water flow along the impeller shaft direction.	High flow rate Low pressure
Radial Flow Pump	This pump type produces flow in a direction perpendicular to the shaft (90° angle).	Low flow rate High pressure
Mixed Flow Pump	This pump type combines radial and axial flow, producing a conical flow pattern around the shaft.	Medium flow rate Medium pressure