Strainers have various important roles for chemical plant

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Strainers are becoming more and more used as piping parts in chemical plant piping.

We have summarized the types and usage.

I think of strainers and filters separately for convenience.

  • strainer small
  • filter   large

It’s a fairly appropriate use, but I’ve arbitrarily categorized them by size.

This time it’s a strainer.

When attaching a strainer to piping, consider it as a set including incidental parts .

Failure to do so may cause unexpected trouble.

Strainers are surprisingly dangerous

In that sense, it feels similar to an in-line flow meter.

Strainer configuration

Generally, the configuration of a strainer follows the rules below.

Regarding equipment under the proviso to Article 272, Item 2 of the Industrial Safety and Health Regulations and the proviso to Article 16, Item 2 of the Specified Chemical Substance Hazard Prevention Ordinance

This example states that four elements are required for the strainer removal operation.

  • inlet outlet valve
  • drain valve
  • Air bleed valve
  • pressure gauge

Identify each part and its purpose.

Strainer structure

inlet outlet valve

Valves are required at the inlet and outlet.

Without these valves, the strainer cannot be removed.

At least the entrance side is required.

This is because there is a very low possibility that there is no liquid on the inlet side.

There are conditions on the exit side, but it is basically required.

The condition is that the container in the outlet line is empty.

If the valves are located close to the strainer for both the inlet and outlet, you only need to drain the liquid around the strainer, which increases safety.

If you are concerned about shutting off with one valve, consider installing two valves in series .

drain valve

In order to remove the strainer, it is necessary to drain the liquid.

A drain valve is required to shut off the inlet and outlet valves and drain the liquid inside the strainer.

Small strainers are available in 15A and 20A, but it is best to use as large a strainer as possible.

I want 25A .

This is because we do not know the viscosity, sedimentation, occlusion, etc. of the substances we are handling .

In the past, 15A may have been sufficient to remove liquid, but no process has been developed to improve the liquid removal properties.

I think the bigger one is safer.

The drain drain is usually attached to the bottom of the housing.

In rare cases, there are patterns attached to the sides.


It is still acceptable if the nozzle is attached to the side and in contact with the bottom plate, but there are some manufacturers that do not touch the bottom plate and hit the side 100 to 200 mm above the bottom plate .

This is completely unacceptable.

Air bleed valve

When opening the drain valve, open the air bleed valve first.

If you don’t, you won’t be able to drain the drain properly.

Remember when you turn a plastic bottle upside down to drain the water?

As the water inside the plastic bottle comes out, air must be mixed in.

Here water flows out and air flows in at the same time, creating pulsation.

Water is fine, but if it’s a chemical whose properties are unknown, the liquid may not drain completely.

If you remove the strainer in this state, the liquid remaining in the housing will be exposed to the outside along with the strainer and will come into contact with the chemical solution.

No matter how much you wash, the liquid inside the housing cannot be completely cleaned.

It is dangerous to touch.

That risk should be minimized.

Any 15A or 20A would be fine here.

If possible, it is preferable that it be the same size as the drain or larger.

This is because gas has a lower density than liquid, and even if the amount of air that escapes from the liquid comes in, if the diameters of the drain and air vents are the same, the pressure drop will be greater on the drain side, which has a higher density.

pressure gauge

The above standard recommends that a pressure gauge be attached to either the primary or secondary side.

I am basically against this.

Should be attached to both the primary and secondary sides.

Also, if it can only be attached to either the primary or secondary side, it should be attached to the primary side .

You don’t have to think about it too hard.

All you have to do is think about how to remove trash from the kitchen sink and bathroom.

Debris accumulates on the primary side.

If the inlet and outlet valves are closed and the strainer is clogged, high pressure liquid may remain on the primary side.

Attach a pressure gauge to ensure that this can be removed by draining .

I didn’t have this pressure gauge, and when I tried to open the strainer, the internal liquid came gushing out!

This problem doesn’t just happen once or twice.

Even if the reading on the pressure gauge is zero, it does not prove that there is no internal fluid.

This is a place where you definitely want to install a local pressure gauge .

Y type strainer

A Y-type strainer is, as the name suggests, a strainer shaped like the letter Y.

Y strainer

A strainer is included in the long part of the Y.

The process liquid passes inside the strainer, passes through the strainer, and exits to the outside.

The structure is such that solids are collected by a strainer.

The strainer has the shape of a circular tube with holes on its surface.

There are various hole shapes.

There are many patterns with evenly spaced circles.

It is called punching metal .

The performance of the strainer can be determined by the hole arrangement and hole diameter .

If you do not make the strainer tube long until the total area of ​​the holes is about the same as the cross-sectional area of ​​the piping, the pressure loss will be too much and the liquid will not be able to flow.

The reason why you want to make the strainer longer by making it Y-shaped is to reduce pressure loss .

For normal use

The Y-type strainer is used when it is not very important but you want to remove some solids.

For example, the following locations:

  • nitrogen
  • steam
  • water
  • caustic soda

This is used when you want to ensure a certain level of quality for input during the process .

It is required to be installed in a low-cost, high-volume line, and uses a Y-type strainer.

Since the piping diameter is small such as 25A or 40A, inspection and cleaning are easy.

for firefighting

Y-type strainers are commonly used for firefighting equipment.

For example, consider water spray fire extinguishing equipment as a firefighting equipment.

Firefighting water is the same water that is in the reservoir. It’s full of garbage.

If this water is passed through the fire equipment, it will become clogged.

In particular, the outlet, the water spray nozzle, has a small cross-sectional area, so it gets clogged.

To prevent this from happening, it is common to use a strainer .

The Fire Service Act requires that the opening area of ​​the strainer be at least four times the cross-sectional area of ​​the piping .

In this sense, we have to manage it differently from normal use.

Fire extinguishing equipment generally has a large diameter such as 150A or 200A.

In this case, the strainer becomes an extremely large piece of equipment, and just removing and installing the strainer is a difficult task.

bucket strainer

Bucket strainers are simply different in shape from Y-shaped strainers.

It has a bucket shape.

The structure is simple.

It is effective because it is simple.


Because bucket strainers have a simple structure, they can be made from a variety of materials.

Not only general carbon steel and stainless steel, but also fluororesin are suitable.

There is a strong need to remove solids from corrosive liquids in chemical plants, and bucket strainers are useful as strainers in process lines.

scraping type

The bucket strainer can be equipped with a scraping device .

Perfect for the feeling of cleaning the garbage removal device in the kitchen sink!

Set the brush inside the strainer, connect it to the outside handle, and turn the handle.

Now, if you remove the dust from the strainer and backwash it, it is possible to remove foreign matter to some extent.

You can choose between manual or electric handles.

A large strainer can be difficult to install and remove, so I definitely want to consider a scraping type.


Cleaning of lines with strainers must be considered.

There are many problems where the liquid does not come out even after a simple blow blow.

So what should we do?

Remove strainer and blow

If the strainer is causing obstruction to blowing, it is necessary to remove the strainer or switch to a bypass line.

There is no problem if the line can do this.

If you remove the strainer, the liquid will leak, or you will have to remove it and put it back in place, which will reduce the amount of product, so you don’t want to do that.

Switching to a bypass line requires an automatic valve, so is it possible to spend that much money? There is a problem.

Pump another cleaning solution

This method uses a strainer to clean the objects that cause the clog.

This also requires a cleaning fluid line and an automatic valve, so there are not many opportunities to apply it.

Provide a blow line at the outlet of the strainer

If you continue to use the strainer, dirt will accumulate and the pressure loss will increase, making it impossible to send liquid.

I have to do some cleaning here.

Strainers often have a nitrogen blow line on the primary side .

But this alone is not enough.

Attach a nitrogen blow line to the secondary side of the strainer as well.

You can also expect backwashing effects.

Nitrogen blow (strainer)


There are two types of strainers: those that are treated as equipment and those that are treated as piping.

I think there are many patterns that can be considered piping, so I would like to study this as part of my plumbing studies.

created by Rinker
¥3,080 (2024/03/01 16:27:24時点 Amazon調べ-詳細)

Related article

If you want to know more, check out the article below.

Related information



I explained strainers for chemical plants.

We have described the functions of the vent, drain, valve, and pressure gauge, as well as the Y type and bucket type.

Blow as a cleaning method is also mentioned.

It has functions such as product guarantee, prevention of foreign matter contamination, and prevention of piping blockage. It’s important.

Please feel free to post any concerns, questions, or concerns you may have regarding the design, maintenance, and operation of chemical plants in the comments section. (The comment section is at the bottom of this article.)

*We will read all comments received and respond seriously.