A horizontal beam or bar that is used for structural support is known as a purlin. Purlins are mostly used below the roof and are supported by the building&#;s walls or rafters. We can also say that purlins reinforce the rigid framing by bringing the rafters together. Steel purlins are frequently used in metal buildings, but sometimes they are used to replace closely spaced rafters in wood-frame structures.
Nowadays, purlin manufacturers commonly produce two types of purlins- Z and C purlins. Before diving into the differences between these two, let's see what they actually are.
C Purlin -
As the name implies, C purlins are shaped like the C alphabet and are primarily used to support walls and floors. As one side of this purlin is plain, it is preferred for cladding. These purlins are also perfect for simple span construction.
Z Purlin -
The shape of Z purlins is similar to that of the Z alphabet. They are mostly made using cold-formed or rolled sheets. As compared to hot-rolled angles, Z purlins are known to save up to 50% on structural sheets.
1. Usage:
C purlins are built to shape a building&#;s shell structure walls and floor joists, whereas Z purlins are built to shape a building&#;s shell structure&#;s roof and wall joists.
2. Angles:
Z and C purlins have different angles. The C purlin has an angle of 90 degrees, and the Z purlin has an angle that is less than 90 degrees. Due to this, Z purlins are more flexible than C purlins and can be used for a variety of purposes.
3. Overlapping:
Z purlins can be overlapped continuously, whereas C purlins cannot. Therefore, in metal buildings made for longer spans, it would be better to use Z steel purlins.
4. Roof Sloping:
If a roof slope is small, the difference between the modulus of the flexural section of Z purlin is slightly larger than that of C purlin. But if the roof slope increases, the modulus of the flexural section of a Z purlin will also symmetrically increase vertically. Hence, Z purlins are better suited for roofs with large slopes.
5. Support:
Z purlins usually sit between roofing sheets to provide support while C purlins are used for supporting the beams required for flooring.
6. Strength:
Z Purlins are extremely strong and can support heavy structures although, C purlins have relatively less strength. Therefore, in buildings with a bigger roofing or loading capacity, Z purlins would be a better choice. They are commonly used in agricultural and industrial buildings.
7. Installation:
C purlins are easy to install but Z purlins require more effort and skills. Due to this, it&#;s a good idea to use them on the roofing of steel-framed structures with single spans.
As mentioned above, Z and C purlins may have their differences but both contribute significantly towards a structure. Just like a coin has two sides, similarly, both the purlins have their own set of pros and cons. Therefore, Z and C purlin manufacturers insist on understanding both the purlins comprehensively to make a wise choice and invest in the one that suits a structure best.
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We understand that choosing the right sensor is a daunting task, as there is no real industry standard on how you go about selecting one. There are also some challenges you may encounter, including finding the compatible instrumentation or requiring a custom product that would increase the product&#;s delivery time. We've outlined some steps to help you get started on choosing the perfect load cell for your application.
Step 1 - Understand what you are measuring
After you've determined your application, define what you want to measure. Do you want to measure load? This means that you want to convert input mechanical force into an electrical signal. Note that load cells are different from pressure sensors. Load cells can be used to measure surface pressure. You would use a pressure sensor if you need to measure fluid or gas pressure. Load cell applications include pressure-to-viscosity/liquid separation, automation, medical bag weighing, and many more. Here are a few examples of load cell applications that may help guide you in your selection.
Step 2 - Define key characteristics
Next, you should take a look at some of the characteristics that would define your needs. Do you have a static load or a dynamic load? Define the mounting type. How will you be mounting this load cell? Is it female/male thread, in-line, side mount, flange mount, thru-hole, or compression washer? What is your load direction? (Tension, compression, or both?)
Step 3 - Determine your capacity requirements
Define your minimum and maximum capacity requirements. Be sure to select the capacity over the maximum operating load and determine all extraneous loads and moments before selecting the capacity. Note: if the correct load is not selected, extraneous loads and moments increase combined stress which accelerates fatigue and will also affect the performance and accuracy. Most in-line sensors such as an S-Beam load cell are not designed with extraneous load and moment capabilities. For endurance or fatigue applications, try to operate at 50% or lower of the rated capacity or use a fatigue rated sensor.
Step 4 - Define your size requirements
Next you need to define your size requirements (width, weight, height, length, etc.) and specification requirements (output, nonlinearity, hysteresis, creep, bridge resistance, resolution, frequency response, etc.) You also should recognize if your application will be submersible or exposed to water, or will experience cryogenic or high temperatures.
After you've followed the above steps, you'll have a better idea of what load cell you will need. Below are the most common types of load cells for your reference:
In-Line Load Cells - Most commonly referred to as an in-line load cell with male threads. This style of sensor can be used in both tension and compression loading applications. In-line load cells offer high accuracy and high stiffness with minimal mounting clearance needed. They are great for endurance, off-center, and press applications.
Column Load Cell &#; FUTEK provides a wide range of Canister Load Cells (also known as Column Load Cell) designed for high capacity compression applications such as CNC Machine Vise Clamping Force Test. These models offer robust construction with a capacity ranging from 2,000 to 30,000 lbs. FUTEK has also developed a miniature Load Cell Canister series for applications where size is a critical factor.
Load Button Load Cells - These load cells have a single flat, raised surface (aka a button) where the compressive force is applied. What's impressive about load buttons is their low profile design. As small as they are, they are known for their robustness and are used in fatigue applications.
S-Beam Load Cells - With other names including Z-Beam or S-Type load cells, the S-Beam is a tension and compression sensor with female threads for mounting. Sporting high accuracy and a thin, compact profile, this load cell type is great for in-line processing and automated control feedback applications, such as in wire crimp pull tester machines.
Thru-Hole Load Cells - Also known as donut load cell or washer load cell, these sensors traditionally have a smooth inner diameter used to measure compressive loads that require a rod to pass through its center. One of the primary uses of this sensor type is to measure bolt loading.
Pancake Load Cells - Pancake, canister-style, or universal load cells have a central threaded hole for measuring loads in either tension or compression. These load cells are used in applications needing high endurance, high fatigue life, or high-capacity in-line measurements. They are also highly resistant to off-axis loading.
Rod-End Load Cells - This load cell type offers one male thread and one female thread for mounting. The male and female thread combination is well suited in applications where you need to adapt a sensor into an existing fixture.
Consider purchasing a full system:
If you need an instrument for your application, be sure to select one instrument at the same time you select your sensor. Once you've chosen an instrument to go with your sensor, we recommend choosing a full system calibration. A full system calibration ensures that your sensor and instrument are fully compatible so that you can easily plug and play.
Remember, these tips are guidelines to help point you in the right direction when selecting your sensor. It is crucial to find a sensor manufacturer that has the proven experience and resources to support your needs. Find out if the company has worked with similar applications in the past. If it is a new application in which there is no precedence, select a company that has a reputation for taking on these new challenges and would be able to work with you every step of the way from design through to manufacturing and implementation. If you require a custom product, note that your expected delivery time will increase by at least one month.