Air-diaphragm pumps (double diaphragm pumps) are one type of positive displacement pump. Their main applications are to transfer fluid, low pressure spray, and other low-pressure applications requiring less than 120 psig. They do not meet either ANSI or API standards and are most often used because of their profitability and ability to run on compressed air.
A rotary valve, also known as a rotary-motion valve, rotary airlocks, or rotary feeders, controls the flow of liquid or gas through the connected pipes by rotating one or more passageways in a transverse plug. The function of rotary valve is to meter the flow of granular bulk or powders. With small pressure loss, material enters the valve by a hopper or other inlets, processed by the valve rotor, and then deposited in discrete packets onto a conveyor system.
Purpose of Rotary Valves
The major purposes of rotary valves are:
The flow of liquids and gases can be controlled using valves in a variety of settings. Valves come in a variety of types, functions, porting, durability, and control capabilities. On the other hand, plug valves and ball valves serve the same purpose. They both regulate the flow of gas or liquid using either a straightforward on/off function or a multipath function. So, what are the differences between those valves?
In this post, I want to share the differences between ball valves and plug valves in terms of body structure, function, application, and maintenance. And on the last post, we will learn how to choose the right one. Before we jump into the difference between those valves, let’s learn some basics about ball valves and plug valves.
Ball valves are valves with an internal spherical disc. There is a port, or hole, in this disc. When the port and both ends of the valve are lined up, the valve is in the open position, enabling the medium to freely flow through it. When the port is perpendicular to the ends of the valve, the valve closes, and the medium flow stops. Read More
In this post, I want to share to you general selection guidelines of rotary pumps.
Rotary pumps are positive displacement pumps. However, they are different from reciprocating pumps because they have relatively steady and non-pulsating flow. Rotary pumps are generally selected to handle very high viscosity fluid or if the flow rate is too low to be handled economically by other pumps.
There are several common applications of rotary pumps:
Before we jump into the general selection guidelines of rotary pumps, I think we need to understand several terms that related to rotary pumps, such as slip, volumetric efficiency, and mechanical efficiency, and of course several types of rotary pumps. Read More
In this post, I want to share the approximate efficiencies of centrifugal compressors and axial-flow compressors. We may have already heard about these terms: polytropic efficiency and isentropic (adiabatic) efficiency. What are those?
Polytropic efficiency is frequently used in compressor evaluation. It is frequently referred to as small stage efficiency. The polytropic process is a modification of the adiabatic process, involving an efficiency to represent actual conditions more closely. The performance of centrifugal compressors is frequently compared using the polytropic compression method.
On the other hand, isentropic (adiabatic) efficiency compares actual compression to an ideal compression (adiabatic) in which no heat is exchanged with the environment and no losses are produced (no viscosity and reversible). It is isentropic because it is adiabatic and reversible. The adiabatic process that compresses with the least amount of work is hence the isentropic process. Read More
In this post I want to share a handy method to estimate pump power requirement. Pump power is a function of these parameters:
In this post I want to share how to calculate sonic velocity. Before we jump into the equation, let’s review about sonic velocity briefly.
Sonic velocity or critical velocity is the maximum velocity that can be attained by a compressible fluid. We usually use this parameter in sizing pipe, control valve, and flare.
Sonic velocity is a function the following parameters:
The molecular weight is expressed in absolute temperature, therefore we will use temperature unit of oR or oK. Read More
In this post I want to share how to check if a horizontal pipe carrying liquid is full or partially full. We can use the following criteria to check:
For partially full pipe, we need to do partially full flow analysis as follows.
x = ln (Q/d2.5)
Then we calculate height of liquid in the pipe using the following equation:
H/D = 0.446 + 0.272x + 0.0397x2 – 0.0153x3 – 0.003575x4 Read More
Let’s learn the basic filtration equation which may be useful in sizing and evaluating many types of filtration unit. Disclaimer, this is also the first time in my working life learning about filtration equation, so if you find any mistakes, please feel free to comment below.
There are two terms in basic filtration equation. The first is, if the filtration occurs at constant pressure. And the second is, if the filtration occurs at constant flow rate. If the filtration occurs at constant pressure, then the flow rate will progressively diminished because the filter bed is steadily growing in thickness. Whereas, if the filtration occurs at constant flow rate, then the pressure must be gradually increased.
In previous post, I shared several types of filtration methods and more about cake filters. In this post, I want to share to you several types of clarifying filtration.
Read also: Introduction to Filtration
Read also: Many Types of Cake Filters
The main objective of clarifying filters is to remove small amounts of solids or liquid droplets from either liquids or gases. The liquid may be drinking water, wine, beer, oil, etc., and it is usually the liquid which is the valuable product.
In clarifying filters, the particles are trapped inside the filter medium or on its surfaces. Surface forces catch the particles and immobilize them on the surfaces or within the flow channels.
In general, clarifying filtration are categorized into liquid clarification and gas cleaning. Read More
