CN216448279U - Air treatment positive pressure control device for clean room - Google Patents
Air treatment positive pressure control device for clean room Download PDFInfo
- Publication number
- CN216448279U CN216448279U CN202122423419.6U CN202122423419U CN216448279U CN 216448279 U CN216448279 U CN 216448279U CN 202122423419 U CN202122423419 U CN 202122423419U CN 216448279 U CN216448279 U CN 216448279U
- Authority
- CN
- China
- Prior art keywords
- air
- filter
- clean room
- differential pressure
- sensor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B30/00—Energy efficient heating, ventilation or air conditioning [HVAC]
- Y02B30/70—Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating
Landscapes
- Ventilation (AREA)
- Air Conditioning Control Device (AREA)
Abstract
The utility model relates to the technical field of air treatment, in particular to a positive pressure control device for air treatment of a clean room.
Description
Technical Field
The utility model relates to the technical field of air treatment, in particular to a positive pressure control device for air treatment of a clean room.
Background
Along with the development of electronic factory buildings, lithium batteries and biopharmaceuticals, clean rooms are used more and more. The clean room must maintain a positive pressure differential with the surrounding space. The pressure difference between the clean rooms of different grades is not less than 5Pa, the pressure difference between the clean area and the non-clean area is not less than 5Pa, and the pressure difference between the clean area and the outside is not less than 10 Pa.
For the whole system, the pressure difference balance of the system needs to be maintained, the positive pressure control is not good, and the larger the air volume needed for maintaining the pressure difference is, the higher the energy consumption of the system is. In the operation process, because door and window are opened, the filter laying dust all can cause the influence to indoor outer differential pressure to destroy indoor cleanliness factor, cause the influence to the production environment. At present, the positive pressure control of a clean room mainly comprises the following steps: (1) the system has the advantages that the air supply and return of the system both use constant air volume valves, and the air supply and return are not regulated, so that the elimination capacity of the system for the disturbance of the pressure difference caused by the opening and closing of a clean room, the entrance and exit of personnel and materials is almost 0, and the stability of the pressure difference under the dynamic condition can not be well ensured; (2) the air supply and return of the system are regulated by using a variable air volume valve, the regulation disorder phenomenon often occurs as a result, and if a plurality of parameters are changed, an automatic control system is not suitable; (3) utilize pressure differential sensor direct detection indoor and outdoor pressure differential, control fan frequency conversion operation, there is serious hysteresis in this kind of mode control, in order to maintain the requirement of workshop environment, often keeps a pressure differential more than actual demand, causes the system operation energy consumption height, and indoor pressure differential fluctuation is big simultaneously. The control methods have the problems that the essence of indoor positive pressure fluctuation cannot be correctly reflected, the control device has poor flexibility and serious hysteresis, and the indoor air pressure fluctuation is large, so that the energy consumption of system operation is high.
Disclosure of Invention
The utility model provides a positive pressure control device for air treatment of a clean room, which aims at the problems in the prior art, and is characterized in that the working pressure difference of an air treatment assembly is detected in real time through a first pressure difference sensor, a second pressure difference sensor and a third pressure difference sensor, a controller adjusts the operation of a fan according to the pressure difference to dynamically adjust the positive pressure of the clean room, a door switch induction sensor is used for detecting a door switch signal of the clean room in real time, and the controller adjusts the opening degree of an air return valve according to the door switch signal, so that the pressure difference between the clean room and the outside is kept in a normal range.
In order to solve the technical problems, the utility model adopts the following technical scheme: a positive pressure control device for air treatment of a clean room comprises a controller, an air flow pipeline, an air treatment assembly and a pressure difference treatment assembly, wherein the air treatment assembly comprises a primary filter, a secondary filter and a high-efficiency filter, and the pressure difference treatment assembly comprises a first pressure difference sensor, a second pressure difference sensor, a third pressure difference sensor, a door switch induction sensor, a fan, a frequency converter and a return air valve; the air outlet of the clean room is communicated with the outlet of the primary filter through an air flowing pipeline, and the air return valve is arranged on the air flowing pipeline; the inlet of the primary filter is communicated with external air, the fan is positioned between the primary filter and the intermediate filter, the fan is used for sending air into the intermediate filter, the intermediate filter is communicated with the high-efficiency filter through an air flow pipeline, and the high-efficiency filter is communicated with the clean room; the first differential pressure sensor, the second differential pressure sensor, the third differential pressure sensor and the door switch induction sensor are in signal connection with the controller, and the controller is in signal connection with the frequency converter; the first differential pressure sensor is used for detecting the differential pressure between the inlet and the outlet of the primary filter, the second differential pressure sensor is used for detecting the differential pressure between the inlet and the outlet of the medium-efficiency filter, the third differential pressure sensor is used for detecting the differential pressure between the inlet and the outlet of the high-efficiency filter, and the door switch induction sensor is used for detecting the opening and closing state of a door of a clean room; the controller is used for adjusting the frequency of the frequency converter according to the received pressure difference signal, and the frequency converter is arranged on the fan and used for controlling the rotating speed of the fan; the controller is also used for adjusting the opening degree of the return air valve according to the received opening and closing state of the cleaning chamber door.
Preferably, the first differential pressure sensor is installed in the primary filter, the second differential pressure sensor is installed in the secondary filter, and the third differential pressure sensor is installed in the high efficiency filter.
Preferably, the air treatment malleation controlling means of toilet still includes the shell, establish the air purification chamber in the shell, primary filter, well effect filter and fan are all installed in the air purification chamber in the shell, air inlet and air outlet have been seted up to the shell, and the outside air via air inlet gets into the air purification chamber, via behind primary filter and the filtering action of well effect filter by the air outlet output, the air outlet passes through the air flow pipeline with high efficiency filter intercommunication.
Preferably, the high efficiency filter is installed in a clean room.
Preferably, the positive pressure control device for air treatment of the clean room further comprises a cleaning device, wherein the pressure difference detected by the first pressure difference sensor is greater than the maximum working pressure difference of the primary filter and the pressure difference detected by the second pressure difference sensor is greater than the maximum working pressure difference of the intermediate filter, and the cleaning device is used for cleaning the primary filter and the intermediate filter.
Preferably, the positive pressure control device for air treatment of the clean room further comprises a heat exchanger, wherein the heat exchanger is arranged in the air purification cavity and is positioned between the primary filter and the fan.
The utility model has the beneficial effects that:
1. the pressure difference of the inlet and the outlet of the primary filter is detected by the first pressure difference sensor, the pressure difference of the inlet and the outlet of the intermediate filter is detected by the second pressure difference sensor, and the pressure difference of the inlet and the outlet of the high-efficiency filter is detected by the third pressure difference sensor;
2. meanwhile, a door switch signal of the clean room is detected in real time through a door switch inductive sensor, and then the controller adjusts the opening degree of the return air valve according to the door switch signal, so that the pressure difference between the clean room and the outside is kept in a normal range;
3. the dynamic adjustment mode of the utility model ensures that the control device has high flexibility, avoids the problem of hysteresis, has small air fluctuation, and further reduces the energy consumption of system operation.
Drawings
FIG. 1 is a schematic diagram of the system of the present invention;
FIG. 2 is a signal transmission diagram of the controller and the differential pressure processing assembly of the present invention.
The reference numerals in fig. 1 to 2 include:
1-a controller, 2-an air flow pipeline, 3-a primary filter, 4-a medium filter, 5-a high efficiency filter, 6-a first differential pressure sensor, 7-a second differential pressure sensor, 8-a third differential pressure sensor, 9-a door switch induction sensor, 10-a fan, 11-a frequency converter, 12-an air return valve, 13-a shell, 14-an air purification cavity and 15-a heat exchanger.
Detailed Description
In order to facilitate understanding of those skilled in the art, the present invention will be further described with reference to the following examples and drawings, which are not intended to limit the present invention. The present invention is described in detail below with reference to the attached drawings.
The positive pressure control device for air treatment in a clean room provided by the embodiment, as shown in fig. 1, includes a controller 1, an air flow pipeline 2, an air treatment assembly and a differential pressure treatment assembly, wherein the air treatment assembly includes a primary filter 3, a secondary filter 4 and a high efficiency filter 5, and the differential pressure treatment assembly includes a first differential pressure sensor 6, a second differential pressure sensor 7, a third differential pressure sensor 8, a door switch induction sensor 9, a fan 10, a frequency converter 11 and an air return valve 12; as shown in fig. 1, the outlet of the clean room is connected to the outlet of the primary filter 3 through an air flow duct 2, and the air return valve 12 is installed in the air flow duct 2; the inlet of the primary filter 3 is communicated with outside air, the fan 10 is positioned between the primary filter 3 and the intermediate filter 4, the fan 10 is used for sending air into the intermediate filter 4, the intermediate filter 4 is communicated with the high-efficiency filter 5 through the air flow pipeline 2, and the high-efficiency filter 5 is communicated with the clean room; therefore, a circulating air supply channel is formed between the air processing assembly and the clean room, and new air supply channels are formed between the outside fresh air and the clean room through the primary filter 3, the intermediate filter 4 and the high-efficiency filter 5.
Wherein, the first differential pressure sensor 6 is arranged on the primary filter 3, the second differential pressure sensor 7 is arranged on the middle filter 4, and the third differential pressure sensor 8 is arranged on the high efficiency filter 5; the first differential pressure sensor 6, the second differential pressure sensor 7, the third differential pressure sensor 8 and the door switch induction sensor 9 are in signal connection with the controller 1, and the controller 1 is in signal connection with the frequency converter 11; the first differential pressure sensor 6 is used for detecting the differential pressure between the inlet and the outlet of the primary filter 3, the second differential pressure sensor 7 is used for detecting the differential pressure between the inlet and the outlet of the medium-efficiency filter 4, the third differential pressure sensor 8 is used for detecting the differential pressure between the inlet and the outlet of the high-efficiency filter 5, and the door switch induction sensor 9 is used for detecting the opening and closing state of the door of the clean room; the controller 1 is used for adjusting the frequency of the frequency converter 11 according to the received differential pressure signal, and the frequency converter 11 is installed on the fan 10 and used for controlling the rotating speed of the fan 10; the controller 1 is also configured to adjust the opening degree of the return air valve 12 according to the received open and close state of the clean room door.
Specifically, the air purification is handled for the air after the filtration of circulated air supply and new trend process primary filter 3, medium efficiency filter 4 and high efficiency filter 5, sends into the toilet again, keeps the air quality of toilet, and for control toilet and other outside toilet or outdoor keep stable pressure differential, this embodiment is through carrying out dynamic adjustment to fan 10 and return air valve 12 for the toilet can in time carry out regulation and control to the malleation of toilet when the air fluctuation appears.
In the present embodiment, the first differential pressure sensor 6 detects the inlet/outlet differential pressure Δ Pc of the primary filter 3, the second differential pressure sensor 7 detects the inlet/outlet differential pressure Δ Pz of the intermediate filter 4, and the third differential pressure sensor 8 detects the inlet/outlet differential pressure Δ Pg of the high-efficiency filter 5, the controller 1 calculates the sum Δ Pt of the three differential pressures to be Δ Pc + Δ Pz + Δ Pg, and the controller 1 obtains the initial operation differential pressure signal Δ Pc of the first differential pressure sensor 60Initial operation differential pressure signal Δ Pz of second differential pressure sensor 70And an initial operation differential pressure signal Δ Pg of the third differential pressure sensor 80And summing the three initial differential pressure signals: delta Pt0＝ΔPc0+ΔPz0+ΔPg0。
Performing curve fitting on the performance of the fan 10 to obtain a functional relation between the rotating speed n of the fan 10 and the wind pressure P and the wind quantity Q of the fan 10: n is F (P, Q), and the frequency of the fan 10 is F is np/60, where P is the number of pole pairs of the motor of the fan 10; the controller 1 acquires the wind pressure Pf at the initial operation of the fan 100And air quantity Q0Frequency f0(ii) a The acquisition of the initial operating parameters of the fan 10 is the prior art, and the controller 1 may be connected to the controller 1 of this embodiment through a control device in the fan 10, so as to facilitate the controller 1 to acquire the operating parameters of the fan 10 from the control device of the fan 10;
then through Δ Pt0And Δ Pt calculates the wind pressure P ═ Pf of air blower 100+(ΔPt-ΔPt0) Wherein Pf0For the initial wind pressure of fan 10, F (P, Q) alright obtain rotational speed n again according to the relation n between the wind pressure of fan 10 and the rotational speed n of fan 10, wherein Q is the amount of wind of fan 10, and then can calculate out the real-time frequency F of fan 10 according to rotational speed n, controller 1 sends this real-time frequency to converter 11 again, adjusts the rotational speed of fan 10 through converter 11 to the realization is according to the change of the pressure differential of a plurality of positions the purpose of adjusting the amount of wind of fan 10, and then realizes the effect of the positive pressure of dynamic adjustment toilet.
Further, the present embodiment is provided with a door opening and closing sensing sensor 9 for detecting an opening and closing state signal of the clean room door, and transmitting the detected signal to the controller 1 in real time, and the controller 1 adjusts the opening of the return air valve 12 in real time according to the door opening and closing state signal of the structure, thereby maintaining the pressure difference between the clean room and the outside in balance.
The opening degree of the return air valve 12 is adjusted in the following manner: the controller 1 records the opening X of the return air valve 12 when the air treatment of the clean room is normally performed1(ii) a The return air valve 12 also belongs to an electric device, and the control end of the return air valve can be connected with the controller 1, so that the controller 1 can acquire an opening signal of the return air valve 12 and control the opening of the return air valve 12; the controller 1 acquires an air leakage rate L0 when the door of the clean room is fully opened; the detection of the air leakage rate L0 is the prior art, and can be realized by adopting the existing structures such as a special sensor for detecting the air leakage rate and the like; when the controller 1 detects a door opening signal of the clean room through the door opening and closing induction sensor 9, the controller 1 adjusts and closes the return air valve 12; and the controller 1 records the opening X of the return damper 12 when the fresh air volume increases by L0 in the process of testing the change of the fresh air volume input by the primary filter 3 during the closing of the return damper 122(ii) a Wherein the fresh air volume is the fresh air volume; the clean room is provided with an indoor and outdoor pressure difference detection device, and the controller 1 acquires the indoor and outdoor pressure difference Pn of the clean room through the indoor and outdoor pressure difference detection device; the controller 1 compares the acquired indoor/outdoor pressure difference Pn with a threshold value P0 of the indoor/outdoor pressure difference preset in the controller 1, and calculates a deviation Δ Pn equal to Pn-P0(ii) a The controller 1 performs PID adjustment on the return air valve 12 according to the deviation Delta Pn, so that the opening degree of the return air valve 12 is X1And X2Adjusting; the PID adjusting mode is the prior art; when the controller 1 detects a door closing signal of the clean room through the door opening and closing induction sensor 9, the controller 1 controls the return air valve 12 to return to the initial opening position X1。
In the embodiment, the positive pressure control of the clean room is realized by combining the dynamic adjustment of the fan 10 and the dynamic adjustment of the opening degree of the air return valve 12, so that a balanced pressure difference can be kept between the clean room and the outside no matter the clean room is in a door opening state or a door closing state.
The embodiment provides a positive pressure control device for air treatment of clean room, as shown in fig. 1, positive pressure control device for air treatment of clean room further comprises a housing 13, an air purification chamber 14 is arranged in housing 13, a primary filter 3, a medium efficiency filter 4 and a fan 10 are arranged in the air purification chamber 14 in housing 13, an air inlet and an air outlet are arranged on housing 13, external air enters air purification chamber 14 through the air inlet, the external air is output through the air outlet after the filtering action of primary filter 3 and medium efficiency filter 4, and the air outlet is communicated with high efficiency filter 5 through an air flowing pipeline 2. Wherein the high efficiency filter 5 is installed at a ventilation place of the clean room. The air treatment assembly of this embodiment further includes an air purification structure in the prior art, such as a heat exchanger 15 and a humidity regulator, to keep the temperature and humidity of the air in the clean room within a normal range. Further, this embodiment still includes cleaning device, when the pressure differential that first differential pressure sensor 6 that the controller 1 received detected is greater than the biggest pressure differential of work of primary filter 3, cleaning device washs primary filter 3, when the pressure differential that second differential pressure sensor 7 detected is greater than the biggest pressure differential of work of medium efficiency filter 4, cleaning device washs medium efficiency filter 4, and when the pressure differential that third differential pressure sensor 8 detected is greater than the biggest pressure differential of work of high efficiency filter 5, then need change high efficiency filter 5 to make three filter homoenergetic keep in normal operating condition.
Although the present invention has been described with reference to the above preferred embodiments, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the utility model as defined by the appended claims.
Claims (7)
1. The utility model provides a clean room air treatment malleation controlling means which characterized in that: the air treatment assembly comprises a primary filter, a medium-efficiency filter and a high-efficiency filter, and the differential pressure treatment assembly comprises a first differential pressure sensor, a second differential pressure sensor, a third differential pressure sensor, a door switch induction sensor, a fan, a frequency converter and an air return valve;
the air outlet of the clean room is communicated with the outlet of the primary filter through an air flowing pipeline, and the air return valve is arranged on the air flowing pipeline; the inlet of the primary filter is communicated with external air, the fan is positioned between the primary filter and the intermediate filter, the fan is used for sending air into the intermediate filter, the intermediate filter is communicated with the high-efficiency filter through an air flow pipeline, and the high-efficiency filter is communicated with the clean room;
the first differential pressure sensor, the second differential pressure sensor, the third differential pressure sensor and the door switch induction sensor are in signal connection with the controller, and the controller is in signal connection with the frequency converter; the first differential pressure sensor is used for detecting the differential pressure between the inlet and the outlet of the primary filter, the second differential pressure sensor is used for detecting the differential pressure between the inlet and the outlet of the medium-efficiency filter, the third differential pressure sensor is used for detecting the differential pressure between the inlet and the outlet of the high-efficiency filter, and the door switch induction sensor is used for detecting the opening and closing state of a door of a clean room;
the controller is used for adjusting the frequency of the frequency converter according to the received pressure difference signal, and the frequency converter is arranged on the fan and used for controlling the rotating speed of the fan;
the controller is also used for adjusting the opening degree of the return air valve according to the received opening and closing state of the cleaning chamber door.
2. The clean room air treatment positive pressure control device of claim 1, wherein: the first differential pressure sensor is arranged on the primary filter, the second differential pressure sensor is arranged on the intermediate filter, and the third differential pressure sensor is arranged on the high-efficiency filter.
3. The clean room air treatment positive pressure control device of claim 1, wherein: air treatment malleation controlling means of toilet still includes the shell, establish the air purification chamber in the shell, primary filter, well effect filter and fan all install in air purification chamber in the shell, air inlet and air outlet have been seted up to the shell, and outside air via air inlet gets into the air purification chamber, via behind primary filter and the filtering action of well effect filter by air outlet exports, the air outlet passes through the air flow pipeline with high efficiency filter intercommunication.
4. The clean room air treatment positive pressure control device of claim 3, wherein: the high-efficiency filter is arranged in the clean room.
5. The clean room air treatment positive pressure control device of claim 1, wherein: the positive pressure control device for the clean room air treatment further comprises a cleaning device, wherein the pressure difference detected by the first pressure difference sensor is greater than the maximum working pressure difference of the primary filter and the pressure difference detected by the second pressure difference sensor is greater than the maximum working pressure difference of the intermediate filter, and the cleaning device is used for cleaning the primary filter and the intermediate filter.
6. The clean room air treatment positive pressure control device of claim 3, wherein: the positive pressure control device for air treatment of the clean room further comprises a heat exchanger, wherein the heat exchanger is arranged in the air purification cavity and is positioned between the primary filter and the fan.
7. The clean room air treatment positive pressure control device of claim 3, wherein: the positive pressure control device for the air treatment of the clean room further comprises a humidity regulator, and the humidity regulator is used for adjusting the humidity of the air.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202122423419.6U CN216448279U (en) | 2021-09-30 | 2021-09-30 | Air treatment positive pressure control device for clean room |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202122423419.6U CN216448279U (en) | 2021-09-30 | 2021-09-30 | Air treatment positive pressure control device for clean room |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN216448279U true CN216448279U (en) | 2022-05-06 |
Family
ID=81349370
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202122423419.6U Active CN216448279U (en) | 2021-09-30 | 2021-09-30 | Air treatment positive pressure control device for clean room |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN216448279U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114060919A (en) * | 2021-09-30 | 2022-02-18 | 广东迪奥技术有限公司 | Positive pressure adjusting method and control system for air treatment of clean room |
-
2021
- 2021-09-30 CN CN202122423419.6U patent/CN216448279U/en active Active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114060919A (en) * | 2021-09-30 | 2022-02-18 | 广东迪奥技术有限公司 | Positive pressure adjusting method and control system for air treatment of clean room |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN114060919A (en) | Positive pressure adjusting method and control system for air treatment of clean room | |
| CN109959076B (en) | Room temperature control ventilation system and control method thereof | |
| CN104791963A (en) | Variable air volume (VAV) energy-saving control system for central air-conditioner | |
| CN210135648U (en) | Variable air volume fresh air system based on number feedback adjustment | |
| CN216448279U (en) | Air treatment positive pressure control device for clean room | |
| CN111412561A (en) | Constant temperature and humidity control system and method for semiconductor clean room based on MAU and DCC | |
| CN206556189U (en) | A kind of air conditioner fresh air control system | |
| CN109990445A (en) | A kind of air conditioning system with variable energy-saving controller and method | |
| CN210345777U (en) | Fresh air circulating equipment with air quantity controllable function | |
| CN112303785A (en) | Static pressure air dividing box, fresh air system and operation control method thereof | |
| CN209147369U (en) | A kind of monitoring device of air treatment system | |
| CN212319933U (en) | High-comfort low-energy-consumption five-constant home environment system | |
| CN207365245U (en) | A kind of indoor fresh air ventilating system | |
| CN218495081U (en) | Passive room fresh air conditioning equipment with passive ultralow energy consumption | |
| CN113566254B (en) | Residential kitchen air supplementing method and air supplementing integrated range hood | |
| CN205505323U (en) | Box -like new trend system of two fresh air processing units | |
| Mingsheng Liu PhD | Supply fan control methods for VAV systems using a fan airflow station | |
| CN210663223U (en) | Static pressure air-dividing box, fresh air fan and fresh air conditioner all-in-one machine | |
| CN212538085U (en) | Constant temperature and humidity control system | |
| CN210979963U (en) | Commercial kitchen combination formula system of discharging fume | |
| CN113847659A (en) | Clean room pressure difference gradient control system and control method | |
| CN209569843U (en) | Passive room super low energy consumption house fresh air changes in temperature integrated system | |
| CN206724425U (en) | A kind of cloud terminal control mechanism for global optimization all-air system | |
| CN216204183U (en) | Propeller type variable air volume end device for subway equipment room | |
| CN218721959U (en) | Air conditioning system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| GR01 | Patent grant | ||
| GR01 | Patent grant |