阅读说明：本技术 一种板式换热器超声波清洗装置及清洗方法 (Ultrasonic cleaning device and cleaning method for plate heat exchanger ) 是由 周恒龙 王印周 李振强 李铭 张猛 郑占领 脱子林 于 2020-11-30 设计创作，主要内容包括：本发明涉及一种板式换热器超声波清洗装置及清洗方法,属于冶金行业冷轧带钢生产技术领域。本发明的技术方案是：包括清洗槽(1),位于清洗槽(1)两侧的漂洗槽(2)和控制柜(3)；使用超声波振子(7)对换热片(24)进行无接触式清洗,利用喷梁(21)对初步清洗后的换热片(24)进行漂洗,采用自动控制系统简化清洗操作。本发明的有益效果是：可以实现对板式换热器解体后的换热片做到无损清洗,清洗效果好,且整个清洗过程对环境无污染,同时可以省时省力,提高作业效率。(The invention relates to an ultrasonic cleaning device and a cleaning method for a plate heat exchanger, and belongs to the technical field of cold-rolled strip steel production in the metallurgical industry. The technical scheme of the invention is as follows: comprises a cleaning tank (1), a rinsing tank (2) and a control cabinet (3) which are positioned at the two sides of the cleaning tank (1); the heat exchange fins (24) are cleaned in a non-contact mode through the ultrasonic vibrators (7), the heat exchange fins (24) after primary cleaning are rinsed through the spray beams (21), and cleaning operation is simplified through an automatic control system. The invention has the beneficial effects that: can realize accomplishing harmless washing to the heat exchanger fin after the plate heat exchanger disintegrates, the cleaning performance is good, and whole cleaning process is pollution-free to the environment, simultaneously can labour saving and time saving, improves the operating efficiency.)

1. The utility model provides a plate heat exchanger ultrasonic cleaning device which characterized in that: the cleaning tank comprises a cleaning tank (1), a rinsing tank (2) and a control cabinet (3), wherein the rinsing tank (2) and the control cabinet (3) are respectively positioned at two sides of the cleaning tank (1), an ultrasonic generator (13) and a PLC module (14) are installed in the control cabinet (3), and the ultrasonic generator (13) is connected with the PLC module (14);

the cleaning tank (1) comprises a cleaning tank outer wall (5), a cleaning tank inner container (6), an ultrasonic vibrator (7), an electric heater (16) and a cleaning tank thermometer (25), wherein the cleaning tank outer wall (5) and the cleaning tank inner container (6) are connected in a welding mode; the ultrasonic vibrators (7) are uniformly distributed on five planes of the inner container (6) of the cleaning tank and are connected with an ultrasonic generator (13) positioned in the control cabinet (3); the electric heater (16) is arranged at the bottom of the inner container (6) of the cleaning tank and is staggered with the ultrasonic vibrator (7) at the bottom of the inner container (6) of the cleaning tank, the thermometer (25) of the cleaning tank is arranged at the upper part of the inner container (6) of the cleaning tank, the electric heater (16) and the thermometer (25) of the cleaning tank are connected with the control cabinet (3) through a cable (15), the spray beam (21) is arranged in the vertical direction of the left side and the right side in the rinsing tank (2), and the spray beam (21) is transversely provided with spray holes (23).

2. The ultrasonic cleaning device for the plate heat exchanger according to claim 1, wherein: the cleaning tank (1) is also provided with a cleaning tank water injection electromagnetic valve (8), a cleaning tank water discharge electromagnetic valve (9) and a cleaning tank liquid level meter (10), the cleaning tank water injection electromagnetic valve (8) is installed on a water inlet pipeline at the upper part of the cleaning tank inner container (6), the cleaning tank water discharge electromagnetic valve (9) is installed on a water discharge pipeline at the bottom of the cleaning tank inner container (6), and the cleaning tank liquid level meter (10) is installed at the lower part of the cleaning tank inner container (6) and is used for monitoring the liquid level of the cleaning tank (; the cleaning tank water injection electromagnetic valve (8), the cleaning tank water discharge electromagnetic valve (9) and the cleaning tank liquid level meter (10) are respectively connected with a PLC module (14) of the control cabinet (3).

3. The ultrasonic cleaning device for the plate heat exchanger according to claim 1, wherein: a row of cleaning tank positioning blocks (17) are welded on the left side and the right side of the cleaning tank liner (6), a row of cleaning tank bottom partition plates (18) are welded in the middle of the bottom surface of the cleaning tank liner (6), and the cleaning tank positioning blocks (17) and the cleaning tank bottom partition plates (18) are arranged in a triangular mode in space and used for fixing heat exchange plates (24) in the cleaning tank (1).

4. The ultrasonic cleaning device for the plate heat exchanger according to claim 1, wherein: the ultrasonic vibrator (7) is fixed on the inner container (6) of the cleaning tank through a bolt, the single ultrasonic vibrator (7) adopts 28kHz/60W, the quantity of the ultrasonic vibrators (7) which are uniformly distributed on the front surface, the rear surface, the left surface, the right surface and the bottom of the inner container (6) of the cleaning tank is respectively 66 on the front surface and the rear surface, respectively 30 on the left surface and the right surface and 84 on the bottom, and all the ultrasonic vibrators (7) are connected to an ultrasonic generator (13) which is positioned in the control cabinet (3) in a parallel connection mode.

5. The ultrasonic cleaning device for the plate heat exchanger according to claim 1, wherein: the rinsing tank (2) is further provided with a rinsing tank positioning block (22), a rinsing tank water injection solenoid valve (20) and a rinsing tank water discharge solenoid valve (26), the rinsing tank positioning block (22) is welded on the left side and the right side of the rinsing tank (2), the rinsing tank water injection solenoid valve (20) is installed on a water injection pipeline on the upper portion of the rinsing tank (2), and the rinsing tank water discharge solenoid valve (26) is installed on a water discharge pipeline at the bottom of the rinsing tank (2).

6. The ultrasonic cleaning device for the plate heat exchanger according to claim 1, wherein: the number of the spray beams (21) in the rinsing tank (2) is three, the number of the spray beams (21) in each row is 11, and the spray holes (23) are uniformly arranged on the spray beams (21).

7. The ultrasonic cleaning device for the plate heat exchanger according to claim 1, wherein: the control cabinet (3) further comprises a temperature control system (4), a system starting button (11), a system operation indicator lamp (12), a rinsing starting button (27) and a system stopping button (28), and the temperature control system, the system starting button (11), the rinsing starting button and the system stopping button are installed on the front panel of the control cabinet (3).

8. An ultrasonic cleaning method for a plate heat exchanger is characterized by comprising the following steps:

(1) sequentially placing the heat exchange pieces after the plate heat exchanger is disassembled into a cleaning tank, and ensuring that each heat exchange piece is positioned in a position to be cleaned, which is formed by a positioning block of the cleaning tank and a partition plate at the bottom of the cleaning tank;

(2) switching on a power supply of the device, pressing a system starting button on the control cabinet, automatically opening the system, and automatically closing a water injection electromagnetic valve of the cleaning tank to stop water injection after the water level is over the heat exchange sheet;

(3) after stopping injecting water for a set time, automatically starting the electric heater, and automatically stopping heating when the water in the cleaning tank is heated to a set temperature;

(4) automatically starting an ultrasonic generator, cleaning for a period of time, and then closing the ultrasonic generator;

(5) opening a drainage electromagnetic valve of the cleaning tank, and closing the drainage electromagnetic valve of the cleaning tank after emptying;

(6) moving the primarily cleaned heat exchange fins into a rinsing tank, and ensuring that each heat exchange fin is positioned between positioning blocks of the rinsing tank;

(7) pressing a rinsing start button, automatically opening a water injection electromagnetic valve of the rinsing tank, and performing spray rinsing on the heat exchanger through a spray beam; when the rinsing time is up, closing the water injection electromagnetic valve of the rinsing tank and opening the water discharge electromagnetic valve of the rinsing tank for a certain time;

(8) and pressing a system stop button to finish the cleaning operation.

Technical Field

The invention relates to an ultrasonic cleaning device and a cleaning method for a plate heat exchanger, and belongs to the technical field of cold-rolled strip steel production in the metallurgical industry.

Background

The plate heat exchangers are common cooling equipment in the production process of cold-rolled strip steel in the metallurgical industry, and each plate heat exchanger generally comprises 100-300 heat exchange sheets. The plate heat exchanger usually utilizes normal-temperature industrial water to exchange heat with certain industrial media, so as to achieve the purpose of industrial media temperature reduction. In the process, the circulating water is easy to scale on the heat exchange fins when heated, and if the scale is not cleaned in time, on one hand, the heat conductivity coefficient of the heat exchange fins is greatly reduced, so that the heat exchange effect of the heat exchanger is influenced; on the other hand, dirt can generate under-dirt corrosion on the heat exchange plates, so that the heat exchange plates are damaged or perforated, and the operation of equipment is influenced. The traditional cleaning methods of the plate heat exchanger include two methods, one is cleaning by chemical agents, and the other is cleaning by manual brushing. The cleaning with chemical agents has the following problems: firstly, chemical agent proportioning needs to be carried out on site according to actual conditions, and the process is complicated; secondly, the chemical agent can corrode the heat exchanger, and the service life of the heat exchanger is shortened; thirdly, the discharged matter after cleaning pollutes the environment. The following problems exist with manual brushing: firstly, the force is required to be mastered in the brushing process, otherwise, the plate is damaged, secondly, the surface of the plate is damaged in the brushing process, scaling is more easily caused after the plate is reloaded, and the cleaning period is shortened; thirdly, the cleaning effect is general, and wastes time and labor. Therefore, an ultrasonic cleaning device and a cleaning method for a plate heat exchanger are needed to be designed for solving the problem of cleaning the plate heat exchanger.

Disclosure of Invention

The invention aims to provide an ultrasonic cleaning device and a cleaning method for a plate heat exchanger, which are used for cleaning a disassembled plate of the plate heat exchanger by using ultrasonic waves, can realize non-contact cleaning and protect the plate from being damaged in the cleaning process; the water temperature control system is used for increasing the temperature of the cleaning water, so that the cleaning effect can be improved; residual dirt on the surface of the plate can be cleaned by using the rinsing tank; the cleaning operation can be simplified by adopting an automatic control system; through foretell improvement, can realize accomplishing harmless washing to the heat exchanger fin after the plate heat exchanger disintegrates, the cleaning performance is good, and whole cleaning process is pollution-free to the environment, simultaneously can labour saving and time saving, improve the operating efficiency, solved the above-mentioned problem that exists effectively among the background art.

The technical scheme of the invention is as follows: an ultrasonic cleaning device for a plate heat exchanger comprises a cleaning tank, a rinsing tank and a control cabinet, wherein the rinsing tank and the control cabinet are respectively positioned on two sides of the cleaning tank, an ultrasonic generator and a PLC module are installed in the control cabinet, and the ultrasonic generator is connected with the PLC module;

the cleaning tank comprises a cleaning tank outer wall, a cleaning tank inner container, an ultrasonic vibrator, an electric heater and a cleaning tank thermometer, wherein the cleaning tank outer wall and the cleaning tank inner container are connected in a welding mode; the ultrasonic vibrators are uniformly distributed on five planes of the inner container of the cleaning tank and are connected with an ultrasonic generator positioned in the control cabinet; the electric heater is arranged at the bottom of the inner container of the cleaning tank and is staggered with the ultrasonic vibrator at the bottom of the inner container of the cleaning tank, the thermometer of the cleaning tank is arranged at the upper part of the inner container of the cleaning tank, and the electric heater and the thermometer of the cleaning tank are connected with the control cabinet through cables.

Spray beams are vertically arranged on the left and right surfaces in the rinsing tank, and spray holes are transversely formed in the spray beams.

The cleaning tank is also provided with a cleaning tank water injection electromagnetic valve, a cleaning tank water discharge electromagnetic valve and a cleaning tank liquid level meter, wherein the cleaning tank water injection electromagnetic valve is arranged on a water inlet pipeline at the upper part of the cleaning tank inner container; and the cleaning tank water injection electromagnetic valve, the cleaning tank water drainage electromagnetic valve and the cleaning tank liquid level meter are respectively connected with the PLC module of the control cabinet.

A row of cleaning tank locating blocks are welded on the left side and the right side of the cleaning tank inner container respectively, a row of cleaning tank bottom partition plates are welded at the middle position of the bottom surface of the cleaning tank inner container, and the cleaning tank locating blocks and the cleaning tank bottom partition plates are arranged in a triangular mode in space and used for fixing the heat exchange plates in the cleaning tank.

The ultrasonic vibrators are fixed on the inner container of the cleaning tank through bolts, a single ultrasonic vibrator is 28kHz/60W, the number of the ultrasonic vibrators which are uniformly distributed on the front face, the rear face, the left face, the right face and the bottom of the inner container of the cleaning tank is 66 on the front face and the rear face, 30 on the left face and the right face and 84 on the bottom, and all the ultrasonic vibrators are connected to an ultrasonic generator located inside the control cabinet in a parallel mode.

The potcher still is equipped with potcher locating piece, potcher water injection solenoid valve and potcher drainage solenoid valve, and potcher locating piece welding is on the left and right sides of potcher, and potcher water injection solenoid valve is installed on potcher upper portion water injection pipeline, and potcher drainage solenoid valve is installed on the drainage pipe of potcher bottom.

The number of spray beams in the rinsing tank is three, 11 spray beams are arranged in each row, and spray holes are uniformly formed in the spray beams.

The control cabinet also comprises a temperature control system, a system starting button, a system running indicator light, a rinsing starting button and a system stopping button which are arranged on the front panel of the control cabinet.

An ultrasonic cleaning method for a plate heat exchanger comprises the following steps:

(1) sequentially placing the heat exchange pieces after the plate heat exchanger is disassembled into a cleaning tank, and ensuring that each heat exchange piece is positioned in a position to be cleaned, which is formed by a positioning block of the cleaning tank and a partition plate at the bottom of the cleaning tank;

(2) switching on a power supply of the device, pressing a system starting button on the control cabinet, automatically opening the system, and automatically closing a water injection electromagnetic valve of the cleaning tank to stop water injection after the water level is over the heat exchange sheet;

(3) after stopping injecting water for a set time, automatically starting the electric heater, and automatically stopping heating when the water in the cleaning tank is heated to a set temperature;

(4) automatically starting an ultrasonic generator, cleaning for a period of time, and then closing the ultrasonic generator;

(5) opening a drainage electromagnetic valve of the cleaning tank, and closing the drainage electromagnetic valve of the cleaning tank after emptying;

(6) moving the primarily cleaned heat exchange fins into a rinsing tank, and ensuring that each heat exchange fin is positioned between positioning blocks of the rinsing tank;

(7) pressing a rinsing start button, automatically opening a water injection electromagnetic valve of the rinsing tank, and performing spray rinsing on the heat exchanger through a spray beam; when the rinsing time is up, closing the water injection electromagnetic valve of the rinsing tank and opening the water discharge electromagnetic valve of the rinsing tank for a certain time;

(8) and pressing a system stop button to finish the cleaning operation.

The invention has the beneficial effects that: ultrasonic waves are used for cleaning the disassembled plate of the plate heat exchanger, so that non-contact cleaning can be realized, and the plate is protected from being damaged in the cleaning process; the water temperature control system is used for increasing the temperature of the cleaning water, so that the cleaning effect can be improved; residual dirt on the surface of the plate can be cleaned by using the rinsing tank; the cleaning operation can be simplified by adopting an automatic control system; through foretell improvement, can realize accomplishing harmless the washing to the heat exchanger fin after the plate heat exchanger disintegrates, the cleaning performance is good, and whole cleaning process is pollution-free to the environment, simultaneously can labour saving and time saving, improves the operating efficiency.

Drawings

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a front view of the cleaning tank of the present invention;

FIG. 3 is a top view of the cleaning tank of the present invention;

FIG. 4 is a layout view of the front/rear ultrasonic vibrators of the tank liner of the present invention;

FIG. 5 is a left/right ultrasonic vibrator layout view of the inner tank of the cleaning tank of the present invention;

FIG. 6 is a right side view of the rinse tank of the present invention;

FIG. 7 is a top view of a rinse tank of the present invention;

FIG. 8 is a view of the spray beam configuration of the present invention;

in the figure: cleaning tank 1, rinsing tank 2, control cabinet 3, temperature control system 4, cleaning tank outer wall 5, cleaning tank inner container 6, ultrasonic vibrator 7, cleaning tank water injection solenoid valve 8, cleaning tank water discharge solenoid valve 9, cleaning tank liquidometer 10, system start button 11, system operation indicator lamp 12, ultrasonic generator 13, PLC module 14, cable 15, electric heater 16, cleaning tank positioning block 17, cleaning tank bottom partition 18, water pipe 19, rinsing tank water injection solenoid valve 20, spray beam 21, rinsing tank positioning block 22, spray hole 23, heat exchange sheet 24, cleaning tank thermometer 25, rinsing tank water discharge solenoid valve 26, rinsing start button 27, and system stop button 28.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions of the embodiments of the present invention with reference to the drawings of the embodiments, and it is obvious that the described embodiments are a small part of the embodiments of the present invention, rather than all embodiments, and all other embodiments obtained by a person of ordinary skill in the art without creative work based on the embodiments of the present invention belong to the protection scope of the present invention.

An ultrasonic cleaning device for a plate heat exchanger comprises a cleaning tank 1, a rinsing tank 2 and a control cabinet 3, wherein the rinsing tank 2 and the control cabinet 3 are respectively positioned at two sides of the cleaning tank 1, an ultrasonic generator 13 and a PLC module 14 are installed in the control cabinet 3, and the ultrasonic generator 13 is connected with the PLC module 14;

the cleaning tank 1 comprises a cleaning tank outer wall 5, a cleaning tank inner container 6, an ultrasonic vibrator 7, an electric heater 16 and a cleaning tank thermometer 25, wherein the cleaning tank outer wall 5 and the cleaning tank inner container 6 are connected in a welding mode; the ultrasonic vibrators 7 are uniformly distributed on five planes of the inner container 6 of the cleaning tank and are connected with an ultrasonic generator 13 positioned in the control cabinet 3; the electric heater 16 is arranged at the bottom of the inner container 6 of the cleaning tank and is staggered with the ultrasonic vibrator 7 at the bottom of the inner container 6 of the cleaning tank, the thermometer 25 of the cleaning tank is arranged at the upper part of the inner container 6 of the cleaning tank, and the electric heater 16 and the thermometer 25 of the cleaning tank are connected with the control cabinet 3 through a cable 15.

Spray beams 21 are vertically arranged on the left and right surfaces in the rinsing tank 2, and spray holes 23 are transversely formed in the spray beams 21.

The cleaning tank 1 is also provided with a cleaning tank water injection solenoid valve 8, a cleaning tank drainage solenoid valve 9 and a cleaning tank liquid level meter 10, wherein the cleaning tank water injection solenoid valve 8 is arranged on a water inlet pipeline at the upper part of the cleaning tank inner container 6, the cleaning tank drainage solenoid valve 9 is arranged on a drainage pipeline at the bottom of the cleaning tank inner container 6, and the cleaning tank liquid level meter 10 is arranged at the lower part of the cleaning tank inner container 6 and is used for monitoring the liquid level of the; and a cleaning tank water injection electromagnetic valve 8, a cleaning tank water discharge electromagnetic valve 9 and a cleaning tank liquid level meter 10 are respectively connected with a PLC module 14 of the control cabinet 3.

A row of cleaning tank positioning blocks 17 are welded on the left surface and the right surface of the cleaning tank liner 6 respectively, a row of cleaning tank bottom partition plates 18 are welded at the middle position of the bottom surface of the cleaning tank liner 6, and the cleaning tank positioning blocks 17 and the cleaning tank bottom partition plates 18 are arranged in a triangular mode in space and used for fixing the heat exchange plates 24 on the cleaning tank 1.

The ultrasonic vibrators 7 are fixed on the cleaning tank inner container 6 through bolts, a single ultrasonic vibrator 7 is 28kHz/60W, the number of the ultrasonic vibrators 7 which are uniformly distributed on the front and back surfaces, the left and right surfaces and the bottom of the cleaning tank inner container 6 is 66 on the front and back surfaces, 30 on the left and right surfaces and 84 on the bottom, and all the ultrasonic vibrators 7 are connected to the ultrasonic generator 13 which is located inside the control cabinet 3 in a parallel connection mode.

The potcher 2 is also provided with potcher locating blocks 22, potcher water injection solenoid valves 20 and potcher drainage solenoid valves 26, the potcher locating blocks 22 are welded on the left and right sides of the potcher 2, the potcher water injection solenoid valves 20 are installed on the water injection pipeline on the upper portion of the potcher 2, and the potcher drainage solenoid valves 26 are installed on the drainage pipeline at the bottom of the potcher 2.

The number of the spray beams 21 in the rinsing tank 2 is three, the number of the spray beams 21 in each row is 11, and the spray holes 23 are uniformly arranged on the spray beams 21.

The control cabinet 3 further comprises a temperature control system 4, a system start button 11, a system operation indicator light 12, a rinsing start button 27 and a system stop button 28, which are arranged on the front panel of the control cabinet 3.

An ultrasonic cleaning method for a plate heat exchanger comprises the following steps:

(1) sequentially placing the heat exchange pieces after the plate heat exchanger is disassembled into a cleaning tank, and ensuring that each heat exchange piece is positioned in a position to be cleaned, which is formed by a positioning block of the cleaning tank and a partition plate at the bottom of the cleaning tank;

(2) switching on a power supply of the device, pressing a system starting button on the control cabinet, automatically opening the system, and automatically closing a water injection electromagnetic valve of the cleaning tank to stop water injection after the water level is over the heat exchange sheet;

(3) after stopping injecting water for a set time, automatically starting the electric heater, and automatically stopping heating when the water in the cleaning tank is heated to a set temperature;

(4) automatically starting an ultrasonic generator, cleaning for a period of time, and then closing the ultrasonic generator;

(5) opening a drainage electromagnetic valve of the cleaning tank, and closing the drainage electromagnetic valve of the cleaning tank after emptying;

(6) moving the primarily cleaned heat exchange fins into a rinsing tank, and ensuring that each heat exchange fin is positioned between positioning blocks of the rinsing tank;

(7) pressing a rinsing start button, automatically opening a water injection electromagnetic valve of the rinsing tank, and performing spray rinsing on the heat exchanger through a spray beam; when the rinsing time is up, closing the water injection electromagnetic valve of the rinsing tank and opening the water discharge electromagnetic valve of the rinsing tank for a certain time;

(8) and pressing a system stop button to finish the cleaning operation.

Cleaning tank inner tank 6 is welded with cleaning tank positioning block 17 and cleaning tank bottom partition 18, and rinsing tank 2 is welded with rinsing tank positioning block 22, which are used for ensuring heat exchanger plate 24 to be in vertical state in the cleaning and rinsing processes.

In practical application, the cleaning of the plate heat exchanger comprises the following steps:

(1) inserting the heat exchange fins 24 after the plate heat exchanger is disassembled into the cleaning groove positioning blocks 17 of the cleaning groove 1 in sequence, and enabling the lower surfaces of the heat exchange fins 24 to be positioned in the partition plates 18 at the bottom of the cleaning groove;

(2) the power supply of the device is switched on, a system starting button 11 on the control cabinet 3 is pressed, the system automatically opens the water injection electromagnetic valve 8 of the cleaning tank, the liquid level meter 10 of the cleaning tank transmits the liquid level value to the PLC module 14, and when the liquid level reaches a set value A1, the PLC module 14 controls the water injection electromagnetic valve 8 of the cleaning tank to be closed and stops water injection;

(3) when the water injection time A2 is over, the PLC module 14 controls to start the electric heater 16, when the water in the tank is heated to the set temperature A3, the PLC module 14 controls to stop heating, and during the heating, if the temperature is not in the range of A3 +/-A4, the electric heater 16 is started again;

(4) the PLC module 14 starts the ultrasonic generator 13, cleans the time A5 and closes the ultrasonic generator 13;

(5) the PLC module 14 controls to open the rinse tank drainage electromagnetic valve 9, and closes the rinse tank drainage electromagnetic valve 9 after emptying;

(6) extracting the heat exchange plate 24 after the primary cleaning from the cleaning tank 1, and then inserting the heat exchange plate into the rinsing tank positioning block 22;

(7) pressing a rinsing start button 27 on the control cabinet 3, automatically opening a rinsing tank water injection electromagnetic valve 20, performing spray rinsing on the heat exchange sheet 24 through a spray beam 21 until the rinsing time A6 is up, closing the rinsing tank water injection electromagnetic valve 20 and opening a rinsing tank water drainage electromagnetic valve 26 for a certain time A7;

(8) the system stop button 28 is pressed to complete the cleaning operation.