Installation and troubleshooting of the water supply system can only be performed when the pipe parameters are known. It happens that it’s difficult to get to them, but you need to take a measurement. How to measure the diameter of the pipe in this case? For these purposes, various tools are used: vernier caliper, tape measure, ruler, laser sensors, etc. It is not so difficult to use them, but measurements should be taken correctly.
Outer and Inner Diameter
Most often, this design parameter is measured in inches, which are easily converted to centimeters (the value is multiplied by 2.54). First of all, you should decide what needs to be measured: the inner diameter of the pipe or the outer. Products used for water and gas supply are usually measured by the inner diameter. This is due to the fact that this indicator determines the throughput of the structure.
The outer diameter may have different values depending on the wall thickness (the mechanical strength of the whole product depends on it). According to GOST 355–52, each subsequent pipe diameter differs from the previous one in the best throughput (by 50%). Patency of the structure is often called the conditional (nominal) diameter. In this case, the indicator usually differs from the inner diameter (by 1-10 mm). This important parameter is considered the main characteristic of the product, from which they are repelled during the design and installation process.
We measure with a caliper
Using this high-precision instrument, the parameters of various structures are measured. How to measure the diameter of the pipe with a caliper? To do this, you need to separate his lips, insert the product into them and reduce them so that they are pressed to the surface. When closing, the sponges must be parallel to the plane of the pipe section, otherwise the measurement will be incorrect. A caliper also measures the inner diameter. On its reverse side there are sponges that are placed inside the structure and parted to adjoin the walls.
Sometimes it is necessary to measure the diameter of a mounted pipe that is too large. In this case, you can measure the chord with a tool and calculate the diameter mathematically. We spread his sponges to the maximum distance and apply to the pipe. The resulting indicator is the length of the chord. For the calculation, you will also need to measure the height of the jaws of the device. The diameter is calculated by the formula:
D = (2L / 4H) + H.
If the jaws are too long, then you can put some part (bar, etc.). Then the height will be calculated by the formula:
H = H1-H2.
Measure with a ruler and tape measure
If the cross section is visible on the pipe, then the diameter can be measured with an ordinary ruler. We apply it to the cut area so that the scale runs exactly in the center. We take the distance between the desired points (for the inner or outer diameter). The distance between the extreme points will be the outer diameter. If you need an internal size, you can find out the thickness of the walls and subtract them from the resulting figure.
Everything is clear with the ruler, but how to measure the diameter of the pipe with a tape measure? This tool is suitable for solid and large structures, which are difficult to get close to. We wrap the product so that the tape with the scale fits snugly, and find the place of its intersection. The resulting figure is the circumference. To get the diameter, divide it by the number Pi (3.14).
Copy method
If there are no tools at hand, but there is a camera, then you can use the copy method. How to measure the diameter of the pipe? For this:
- we take an object with known sizes (for example, a brick);
- we lay it on the pipe, along its length or next to the cut;
- we photograph this area so that it is possible to estimate the difference in size;
- we carry out calculations according to the photograph;
- according to the received data we estimate the real sizes (it is important to consider the scale).
Measured with a micrometer
High-precision measurements (up to 0.01) of the pipe can be done with a micrometer. It should be noted that it is convenient for them to measure small items. The tool is a bracket equipped with a supporting heel and a stem with a high-precision thread (for screwing a microscrew). On the stem you can see the scale with millimeters and their hundredths. Such equipment allows you to get more accurate indicators.
How to measure the diameter of the pipe with a micrometer? We place the structure between the end of the screw and the heel. We begin to rotate the ratchet knob until it clicks three times. First, look at the lower scale of the stem, showing the number of whole millimeters. We check for risks, which is on the right. If it is not visible, take readings from the drum. If there is a risk, add 0.5 mm to the resulting number. Measurements on the drum are determined relative to the line on the stem between the scales.
Laser sensors
To take measurements from pipes (and not only), modern laser sensors have been created. Their advantages: lack of contact with the surface, the ability to use on different designs (hot, sticky), durability and speed of obtaining results. How to measure the pipe diameter with such sensors? There are several measurement methods.
In laser triangulation, the beam from the sensor creates a spot on the surface of the structure. Behind the laser is a camera-scanner, which sees it at different angles. Using these indicators, the digital processor calculates the distance between the sensor and the product.
We measure the diameter by shading. In this case, the sensor serves as a transmitter and receiver, but they are located in different buildings. Inside it, a laser beam is reflected from a rotating mirror, envelops the measurement area and creates a virtual band of light. Inside the device, a moving beam passes through a special diode, which measures the duration of shading (corresponds to the size of the object).
Another option is the principle of light section. The sensor is equipped with a laser, camera and electronic circuit. The laser creates a line perpendicular to the product, and the camera is located at a certain angle to it. With any curvature, the laser line is deformed, from which the sensors repel when calculating the dimensions.
It was described above how to measure the diameter of the pipe. But it is important to know that some designs have curvature (maximum 1.5 mm per 1 m of length). In this case, they are talking about their ovality. This parameter is determined by the formula: the difference between the large and small diameter is divided by the nominal. Permissible ovality: not more than 1% for pipes with a wall up to 20 mm, not more than 0.8% - with a wall more than 20 mm. This parameter is very important because it affects the operational characteristics of the structure.