How to choose and install a grease trap under the sink

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Clogged sewer pipe in the kitchen - a common phenomenon. Food remains, fat deposits accumulate on the canal walls and prevent free flow of water. To clean the pipes have to use chemicals that harm plumbing fixtures, or resort to mechanical methods - use a cable or plunger.

It is quite possible to reduce the probability of blockage by placing a grease trap under the sink - the device filters drains and prevents grease from seeping into the sewers. The unit is quite useful, but before you decide to buy it, you need to learn more about such a separator, do you agree?

The article discusses in detail the device, characteristics, principle of operation and modifications of grease traps. It also provides guidance on choosing the device, its installation and maintenance.

The content of the article:

  • Types of grease traps under the sink
  • Technical characteristics of grease traps
    • The scheme of the device and the principle of operation
    • Formulas for calculating the required performance
    • Operating requirements for the separator
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  • What are good zhirouloviteli
  • How to choose a device for home
  • Installing a grease trap under the sink
  • Separator maintenance and control
  • Conclusions and useful video on the topic

Types of grease traps under the sink

There are a lot of types of grease traps, and they all have different performance and equipment. This equipment can be classified according to the case material and structural features.

Grease traps can be plastic, fiberglass, metal.

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Plastic grease trap under the sink

Plastic grease traps are sensitive to mechanical stress, so they are made mainly for domestic purposes.

Industrial fiberglass grease trap

Fiberglass grease traps are manufactured primarily for industrial purposes, as they are much stronger than plastic.

Stainless steel grease trap

Stainless steel grease traps will last several decades and will remain as beautiful

Inked metal grease catcher

It is not advisable to strip off paint on painted metal grease traps, as this accelerates the corrosion process.

Plastic grease trap under the sink

Plastic grease trap under the sink

Industrial fiberglass grease trap

Industrial fiberglass grease trap

Stainless steel grease trap

Stainless steel grease trap

Inked metal grease catcher

Inked metal grease catcher

Plastic. Polypropylene and polyethylene are used to make both industrial and very simple household models of grease traps. They are durable, cheap, lightweight and do not require special maintenance. Most grease traps for washing are made of this material.

Fiberglass. These models have increased strength and resistance to chemicals, so they can be installed outdoors and dig into the ground.

Metallic. Stainless steel grease traps can be easily cleaned with hard brushes, without fear of damaging the surface. They look aesthetically pleasing, but they are expensive. Stainless steel and aluminum models are almost eternal, unlike galvanized and painted steel products that can rust over time.

Grease trap with automatic fat removal

Automatic grease traps are often equipped with a special sensor that starts the process of selecting the fat mass when it reaches a certain level.

Separators in private homes can be made independently, and there are not so many structural requirements for them, therefore there are countless variants of this equipment.

However, they can still be divided into the following types:

  1. Grease traps under the sink. They will be discussed in detail below. Such equipment is serviced manually and installed in apartments, houses, small cafes.
  2. Industrial (shop) models. They are used in food processing facilities designed for hundreds of people, in boarding houses and sanatoriums, as well as in food processing enterprises. Often, these models are equipped with filling sensors.
  3. Automatic. They have an electro-autosampling mechanism, which facilitates maintenance and prevents clogging of the adductor and outlet pipes.
  4. Located below the sewer level. Such models are installed in the basement or in the ground. They have a built-in electric pump, which pumps out the purified water to the level of sewage.
  5. Well wells. These are large industrial grease traps in the form of a cylinder, which can be installed in special external wells. Their service is carried out through the hatch.

For domestic needs, it is enough to purchase a conventional grease catcher for washing, which can be serviced independently once every few weeks. These small devices have a simple design and device.

Technical characteristics of grease traps

To choose a separator that will enter the space under the sink, you need to know not only its overall dimensions and device, but also its functionality. Of considerable importance when choosing a device are the individual characteristics of the apartment and the nature of the food of its residents.

The scheme of the device and the principle of operation

Household drains from the kitchen sink contain a lot of fat, which gradually accumulates in sewer pipes. After a few years, this may lead to clogging of the pipeline, the emergence of a persistent unpleasant smell from the decomposition of organic matter and the need sewage washing.

Old fat accumulations are poorly extracted even sanitary cable, therefore, for their removal may require complete dismantling of the sewer system.

Scheme of the device of a grease trap with two partitions

The partitions between the chambers can have holes to increase the capacity of the grease trap during the discharge of a large amount of water into the sink

These problems can be solved by installing a grease trap under the sink.

Such equipment consists of the following elements:

  1. Rectangular case with two openings (inlet and final) located in the opposite ends of a grease trap.
  2. One or more partitions. They slow down the flow of water in the system, preventing fat and solids from entering the sewer system.
  3. Tight-fitting lid. It should have a rubberized gasket so that air from the interior of the grease trap does not penetrate into the kitchen.
  4. Inlet pipe in the form of a short knee.
  5. Exhaust pipe in the form of a tee open on all sides. It has a long part, dropped almost to the bottom of the case and short, ending under the lid.
  6. Ventilation outlet (optional).

The construction of the grease trap causes the principle of its operation. Contaminated water enters the receiving chamber of the grease trap. The entrance can be both side and top. This part of the space is fenced off by one or two partitions. Due to the difference in the densities of water and fat, the latter rise and accumulate there.

The principle of operation of the grease trap

In the absence of a fine mesh in the drain hole of the sink, a large amount of debris accumulates at the bottom of the grease trap, which must also be removed along with the grease during servicing

If the wall is one, then it usually overlaps the lower 2/3 of the cross section of the grease catcher, and if there are two, they are alternately located below and above: the first cuts off solid particles, and the second - fat.

Behind the partitions there is a second chamber, from the bottom of which a water that has already been cleared of grease and impurities is discharged into the sewer.

The fat fraction gradually fills the upper part of the device’s internal space, therefore it is necessary to clean it in a timely manner, without waiting for the moment when the accumulated fats begin to fall into discharge pipe.

Formulas for calculating the required performance

Hoping that the smallest grease trap will be enough for an apartment is not worth it. It is better to calculate the required performance of the equipment in advance, so as not to regret in vain the money spent.

For calculation, a simple formula is used:

P = n * Ps,


  • R - performance in liters per second;
  • n - the number of connected sinks;
  • Ps - the rate at which water enters the separator in liters per second.

Ps can be calculated independently using a bucket or pans with a known volume. To do this, you need to fully open the water tap and notice the time it takes to fill the container. Then calculate how much water will flow out if the tap is open for one second.

The calculation is performed according to the formula:

Ps = V / T,


  • T - time of a set of water in capacity in seconds;
  • V - capacity in liters.

After determining the required performance of the grease trap, you can find out its recommended volume.

The formula for calculating the volume:

V = 60 * P * t,

Where t - the rate of the floating of fat, the value of which for household separators is 6.4 minutes.

Approximate parameters of grease traps for washing

When only one sink is connected to the grease trap, a performance of 0.5-1 cubic meters / hour will be sufficient, depending on the maximum water pressure in the faucet (+)

On the market are grease traps for washing with a capacity of 0.145 l / s and a volume of 50 liters. The smaller capacity of the device simply physically will not allow to effectively perform the function of cutting off fat, so there is no point in acquiring such models.

Operating requirements for the separator

During the operation of the grease trap, it is necessary to follow a number of rules that increase the efficiency of the equipment and help avoid unpleasant odors and water in the kitchen.

Recommendations for the operation of the device:

  1. Water drains should not contain mineral and synthetic oils.
  2. It is not allowed to connect the grease catcher to the toilet.
  3. It is impossible to install pumps before the equipment, because they form a poorly deposited emulsion.
  4. Inlet pipes should be as close to the sink as possible and have a minimum slope of 2 ° C.
  5. Purified water should be sent directly to the sewer.
  6. It is advisable to connect the grease trap to the ventilation - fun pipeif there is a corresponding outlet on the top of the device.

In order to manufacture quality products, manufacturers must adhere to the standards for the manufacture and installation of EN 1825 and DIN 4040-100 grease traps. Access to the texts of these standards is in the range of $ 100.

What are good zhirouloviteli

Although the volume of the fat separator for sewage is small, it occupies a whole section of the cabinet under the sink in the apartments. Therefore, for the installation of such equipment must be a good reason.

The choice of work on the removal of fat deposits

Regular removal of grease from the separator is much cheaper and faster than calling the master for cleaning clogged sewers.

Owners of grease traps note their advantages:

  1. Simplicity of design. You can assemble the separator yourself from the old plastic tank.
  2. Easy installation. To connect the device to the siphon and sewage system, simply connect two pipes with your hands without using a tool.
  3. Ease of maintenance. Remove the top fat enough every few weeks. The cleaning process takes 2-3 minutes.
  4. Pipe protection from clogging. When using a grease trap sewage will last more than a decade without the need for cleaning.
  5. Compactness and the ability to install equipment under the sink.

It is possible to connect the tank filling sensor to the grease trap.

The main task of the grease trap is not the general purification of water, but the separation from it of particles that can settle in sewer pipes and narrow their clearance.

How to choose a device for home

The initial stage of selecting a grease trap is not carried out in a hardware store or on the Internet, but in the planned place of its installation. Before buying a device, you need to decide on a number of parameters that will help narrow down the choices to several models.

First of all, it is worth assessing:

  1. The size of the free space under the sink. It should be noted that there should be a space on top for removing the cover, and on the sides for connecting the pipes.
  2. Diameter of sewer pipes in the kitchen. It is better to buy a grease trap with the same hole size in order not to use additional plastic adapters.
  3. The number of serviced sinks. When calculating performance, account must be taken of the simultaneous flow of effluent from all open taps.
  4. Stock characteristics. With a large amount of solid particles in the drained water, it is recommended to install models of grease traps with several partitions.
  5. The presence of sewer riser or a funnel pipe near the sink - the channel is necessary to prevent breakdown trap on siphon. Models with an air duct are preferred, but the possibility of connecting them to the sewer riser is not in every apartment or house.
  6. Availability of free space for maintenance of equipment. When removing fat, waste with an unpleasant odor can fall behind the body of the grease trap, therefore it should be possible to clean this space.
  7. Body material. For installation under the sink will be enough ordinary plastic grease trap, but if it is open for viewing, then you can buy a more expensive and aesthetic model of stainless steel.
  8. Washing capacity. Sometimes it is required to discharge water from a full sink in one gulp. This amount of fluid is one of the characteristics of the grease trap and is required to be indicated in the instructions.

After taking into account all the above nuances, you can proceed to the direct selection of a suitable device from the options on the market.

Estimated prices for grease traps

The price of a budget plastic zhiroulovitel approximately corresponds to the cost of washing along with furniture, a tap and a siphon, so you need to plan to purchase it in advance (+)

The price of plastic models depends mainly on the volume of the tank and the complexity of the internal device. With the same parameters, it is better to choose a cheaper option, because a more expensive model is unlikely to be better.

Installing a grease trap under the sink

Mounting the grease trap under the sink does not require any special skills or tools. All the necessary fittings can be purchased in the same store where the machine itself is purchased. Additional polypropylene fittings and tubes may be needed only to connect the grease trap with sewage and siphon.

The separator is usually sold in the assembled state, that is, connecting pipes or rubber adapters are already inserted and sealed in its holes. It remains only to open the lid and remove the instruction manual from the tank.

After that, you can complete the installation of the grease trap:

  1. Prepare a working space under the sink.
  2. In some models of equipment, the water inlet knee and the tee for its removal are attached separately, so they need to be inserted into the corresponding holes, after having been lubricated with silicone.
  3. Screw the adapters to the separator if necessary.
  4. Put the grease under the sink.
  5. Smear outside sanitary sealant sewer and siphon pipes that will be connected to the grease trap.
  6. Connect all necessary pipes to the separator and wait for the sealant to harden.
  7. Connect the air duct to the sewer riser, if any.
  8. Open the tap with water and check the tightness of the tank and pipe connections.

If there are no leaks, then the grease trap is ready for operation.

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Stage 1 - Silicone Adapter Lubrication

If a pipe with a fitting is connected using a threaded connection and there is a rubber gasket between them, then lubrication with a sealant can be avoided.

Stage 2 - installation of a grease trap under the sink

In case of insufficient space for maintenance of the grease trap at the installation site, consider the option of a detachable threaded connection of the siphon and sewer

Stage 3 - Screwing the sewer pipe to the grease trap

The sewage pipe from the separator should depart with a minimum slope of 2 degrees

Stage 4 - checking the tightness with warm water

With a small flow it is better not to gloss over this place with sealant, but to disassemble and assemble the joint again.

Stage 1 - Silicone Adapter Lubrication

Stage 1 - Silicone Adapter Lubrication

Stage 2 - installation of a grease trap under the sink

Stage 2 - installation of a grease trap under the sink

Stage 3 - Screwing the sewer pipe to the grease trap

Stage 3 - Screwing the sewer pipe to the grease trap

Stage 4 - checking the tightness with warm water

Stage 4 - checking the tightness with warm water

Since the temperature of the water greatly influences the effectiveness of the grease trap, it is undesirable to install it next to the actively used oven. You also need to protect the separator from the effects of negative temperatures in the presence of water in it, as this can lead to rupture of the tank.

Separator maintenance and control

Maintenance of the grease trap is not the most pleasant procedure, but it is much more unpleasant to clean the clogged sewer pipes.

The frequency of cleaning a household separator depends on several parameters:

  • fat tank volume;
  • family diets, determining the composition of the effluent;
  • temperature of water used.

Due to these factors, the frequency of cleaning the separator can vary from several weeks to several months.

Cleaning the filled grease trap

Before cleaning the grease trap, it is necessary to open the windows for through-ventilation and wear protective gloves, because in the process of fat breakdown harmful bacteria multiply

Careful attention to the level of waste must be paid in the first weeks of operation. It is necessary to periodically open the lid of the grease trap and check the level of solid waste. If the lower layer of fat falls to the level of the outlet, it can become clogged, which will lead to overfilling of the tank and flooding the room.

It is desirable to remove the fat mass when it reaches the level 4-5 cm above the lower edge of the water discharge pipe. To remove the fat, you need to open the tank lid and pull out the upper viscous layer with the help of gloves, a ladle or other improvised device.

After revision of the grease trap, it can be rinsed with hot water for several minutes.

When experimentally set the approximate period of safe operation of the grease trap, you can look into it much less often.

More information about different types of grease catchers for sewage, an overview of popular models, as well as the specifics of mounting a separator inside and outside the room are described in this article.

Conclusions and useful video on the topic

For a better understanding of the internal structure of the grease trap, the characteristics of its work, the rules of installation and maintenance, it is recommended to view the following videos. They will generalize their knowledge and allow them to see how the device works in dynamics.

Installation of a grease trap under the sink:

The work of the grease trap:

Cleaning the grease separator:

Buying and installing a grease trap under the sink helps to avoid many problems in case of sewage blockage. To install the equipment, it is enough to have free space under the sink, because the process of putting the separator into operation is simple and does not require much time.

Looking for an effective grease trap under the kitchen sink? Or have experience using such installations? Please leave comments on the article and share your impressions about the use of grease traps. Contact form is located in the lower block.

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