73 results about "Backflow prevention device" patented technology

The anti-backflow oxygen humidifying device comprises a main water storage bottle, an air inlet pipe, an air outlet pipe and an anti-backflow device, humidifying liquid is stored in the main water storage bottle, and an air outlet is formed in the top of the main water storage bottle; the air inlet pipe comprises an air pipe and an oxygen pipe, and the air pipe and the oxygen pipe provide air and oxygen for the main water storage bottle respectively; the air outlet pipe communicates with the air outlet; the backflow preventing device comprises a first communicating pipe, a first one-way valve, a first temporary storage bottle and a floating plug, the first temporary storage bottle is connected with the main water storage bottle through the first communicating pipe, the first one-way valve is arranged in the first communicating pipe, when preset pressure is reached, the first one-way valve is communicated towards the main water storage bottle, and the floating plug floats in the main water storage bottle; when the liquid level rises to the top of the main water storage bottle, the floating plug can block the air outlet pipe. According to the anti-backflow oxygen humidifying device, the inhalation risk of a patient caused by backflow of humidifying liquid can be effectively prevented.

The utility model relates to a kind of powder backflow prevention devices, including storage bin and filter box, the side fixed mounting of storage bin has feed pipe, fixed mounting is connected with pipe between storage bin and filter box, the other side fixed mounting of filter box has exhaust pipe, the front of filter box is installed with box door, box door is fixedly connected with filter box by bolt, the side installation of box door has filter assembly, filter assembly includes coarse filter plate and fine filter plate, the inside installation of filter box has the anti-backflow component of preventing powder backflow.The utility model can carry out multistage interception to powder by the coarse filter plate and fine filter plate of filter assembly, avoid powder with gas through exhaust pipe and directly discharge, reduce the air pollution caused by powder drift, solve the installation and dismounting structure of existing filter screen more complex, usually need to dismount with the aid of tool, lead to the cleaning, replacement process of filter plate is complicated, consume more time and manpower, affect filtration effect.

The utility model discloses a device for preventing water backflow of an ozone reactor, which can safely, quickly and automatically avoid the risk that water flows back into an ozone generator and comprises the ozone generator and an oxidation reactor, and an ozone outlet of the ozone generator is connected to the oxidation reactor through an ozone delivery pipe. A pressure sensor and a first electric valve are sequentially arranged on the ozone delivery pipe behind the ozone outlet; a water body discharge pipe provided with a second electric valve and an ozone concentration detection sensor is connected into the ozone delivery pipe between the oxidation reactor and the first electric valve; a controller is arranged to control opening and closing of the first electric valve and the second electric valve according to signals of the pressure sensor and give an alarm according to signals of the ozone concentration detection sensor. The device has the advantages of being capable of automatically running to prevent water backflow of the ozone reactor, safe and fast.

The application discloses a sidetracking horizontal well large-diameter open-hole filling and acid washing integrated pipe column and a running method thereof. The pipe column comprises an outer pipe column and an inner pipe column, the inner pipe column is arranged in the outer pipe column, and a casing is arranged outside the outer pipe column. The outer pipe column comprises, from top to bottom, a locking device, an outer channel, a releasing device, a fishing device, a slip, a rubber sleeve, a reverse washing device, a filling outer tool, a backflow prevention device, an open-hole screen pipe and an acid washing outer sealing device. The inner pipe column comprises, from top to bottom, an inner channel, a filling inner tool, a check valve, a jetting pipe, an acid washing inner sealing device, a jet tool, a ball catching device and a bottom liquid flow port. The running method comprises the following steps: drilling fluid injection, pipe releasing, normal mud replacement, tubing pressure test, opening of the locking device, filling, reverse well washing without moving the pipe column, normal rotation releasing, segmented acid washing construction, reverse well washing until the outlet is clean and pipe column lifting. The application has the advantages of short construction period, effective prevention of well wall collapse, short construction period, high safety, and good construction effect.

The utility model relates to the technical field of material guide grooves, and discloses a backflow prevention device for a material guide groove, which comprises an outer frame, the inner side of the outer frame is fixedly connected with a vertical bracket, two transverse brackets, two arc-shaped brackets and a connecting frame, and the connecting frame is used for connecting the transverse brackets above the vertical bracket and the arc-shaped brackets. A conveying assembly used for conveying materials is arranged on the inner side of the outer frame, a plurality of mounting holes are formed in the outer frame, and elastic baffles are detachably connected to the inner sides of the mounting holes through bolts. The conveying assembly comprises rotating shafts, the inner side of the outer frame is rotationally connected with two rotating shafts, the outer sides of the two rotating shafts are both fixedly connected with belt pulleys, and the two belt pulleys are connected through a belt. The tail end of the anti-reverse baffle is in a hook shape, so that the materials are not prone to falling off from the anti-reverse baffle in the conveying process, and reverse flow of the materials is prevented.

To prevent wastewater from flowing backward into a piping member when wastewater flows backward, and to allow wastewater to flow easily when wastewater is not flowing backward.SOLUTION: A piping member 10 comprises a main body 11 having a main body cylindrical portion 15 in which a drain outlet 44 through which wastewater passes is formed, and backflow prevention means 50 capable of closing the drain outlet 44 when wastewater passing through the drain outlet 44 flows backward. The backflow prevention means 50 has a valve body 55 opening and closing the drain outlet 44, and an opening force applying mechanism 57 applying an opening force to the valve body 55 in the direction of opening the drain outlet 44, at least at times other than backflow when wastewater passing through the drain outlet 44 flows backward. The valve body 55 is configured to close the drain outlet 44 when backflow occurs, by applying backflow pressure which is the pressure of the wastewater when the wastewater passing through the drain outlet 44 flows backward.SELECTED DRAWING: Figure 2

The invention relates to the technical field of intelligent bathroom accessories, and provides an integrated waterway system and an intelligent pedestal pan. The integrated waterway system comprises a water supply unit, a water storage unit and an overflow module, the water supply unit comprises a backflow prevention device, and an air gap is formed between the liquid inlet end and the liquid outlet end of the backflow prevention device; a water storage cavity communicated with the water supply unit is formed in the water storage unit; the overflow module comprises a flow guide part and an overflow part, and the flow guide part is arranged on the outer side of the backflow prevention device and covers the splashing area of the backflow prevention device so as to receive and guide splashing water splashing from the air gap; the overflow piece is provided with a water collecting groove used for collecting splashing water, the water collecting groove is communicated with fluid of the water storage cavity, and the water collecting groove is provided with a first overflow opening. By means of the arrangement, the overflow module has the dual functions of splashing water recycling and overflow protection at the same time, so that the safety guarantee is provided for the system while water resources are recycled, and the operation reliability and safety of the system are improved.

The utility model discloses an anti-backflow faucet, which relates to the technical field of faucets and comprises a faucet body, an anti-backflow device is fixedly mounted on the peripheral side of the end, connected with a water pipe, of the faucet body, and an anti-backflow component is clamped at the joint of the faucet body and an annular pipe. The backflow preventing assembly comprises an annular baffle, the inner wall of one side of the annular baffle is fixedly connected with a conical flow blocking ring, and the tip end of the conical flow blocking ring extends into the faucet body. According to the anti-backflow faucet, the anti-backflow device is additionally arranged between the faucet body and the water supply pipeline, the anti-backflow device comprises the annular baffle, the side face of the annular baffle is fixedly connected with the conical flow blocking ring, and the tip end of the conical flow blocking ring is inserted into the faucet body. And the generated backflow impact can reduce the impact force for impacting the water supply pipeline under the obstruction of the conical flow choking ring, so that the damage to the water supply pipeline caused by the backflow impact can be effectively avoided.

The utility model relates to an intelligent detection and alarm sewage reflux prevention device, which comprises a detection pipe, which is arranged on the side wall of a vertical section of a public vertical pipe at a fixed height from the ground and is communicated with the public vertical pipe; the end cover is arranged at one end of the detection tube to seal the detection tube; the probe is arranged on the end cover and used for detecting the water level in the detection pipe; and the alarm is arranged on the end cover and is used for giving an alarm according to a signal of the probe. Due to the dual effects of gravity and water flow impact, the vertical section of the public vertical pipe is not prone to being blocked, the blocked part is usually located on the buried horizontal section, in the sewage back-flushing process, sewage enters the detection pipe firstly and then is detected by the probe before back-flushing into a resident house, and then the alarm gives an alarm. Due to the fact that regurgitation occurs for a period of time from the time when the alarm gives an alarm to the time when indoor regurgitation occurs, sufficient time can be provided for dredging and dealing with the horizontal section of the public vertical pipe as long as the alarm acts in time.

The utility model relates to an industrial drainage pipeline anti-backflow device in the technical field of anti-backflow. The industrial drainage pipeline anti-backflow device comprises an industrial drainage pipe, a water level flow dividing pipe and a floating lever assembly. The floating lever assembly comprises a floating ball, a hinge rod, a linkage shaft, a lever sleeve strip, a hinge shaft, a linkage block, a linkage valve strip, a rotating shaft and a valve element body. The floating lever assembly is adopted, the linkage block enables the linkage valve strip to rotate clockwise, the sealing ring can achieve closing, plugging and anti-backflow treatment on the inner wall of the industrial drainage pipe, and the industrial drainage pipe anti-backflow device has the advantages of being different from an electric control anti-backflow device, more convenient to use and install, capable of being used for a long time in the condition and environment without depending on electric power and high in stability. Therefore, the problems that the device needs to be used through an electrifying means, is difficult to use for a long time in time in the pipeline blockage process without depending on the condition and environment of electric power, and is poor in use stability are solved.

The invention discloses a gravity concentration sludge treatment device. The gravity concentration sludge treatment device comprises two concentration tank units which are arranged in parallel, the power driving assembly is arranged above each concentration tank unit, and the output end of the power driving assembly is connected with the in-tank sludge stirring mechanism; the feed distribution system is communicated with the two concentration tank units; the input end of the co-connection treatment assembly is connected with sludge discharge ports at the bottoms of the two concentration tank units respectively, and the output end is connected with a sludge conveying pump; wherein the co-connected treatment assembly comprises a sludge crushing device and an anti-reflux device, and the sludge stirring mechanism is provided with a dynamic adjusting structure which is radially distributed along the bottom of the tank. The continuous and efficient sludge dewatering effect is achieved through the synergistic effect of the concentration tank units arranged in parallel and the co-connected treatment assembly in combination with the dynamically-adjusted sludge stirring mechanism and the feed distribution system.

The application discloses a backflow prevention device, belongs to the field of flood control equipment, and solves the problems that current flood control devices are low in flood control efficiency and cannot effectively prevent accumulated water from overflowing. A fixed column is arranged on each of the two side retaining walls of a garage entrance, and the fixed column extends along the height direction of the retaining wall. A telescopic rod is arranged in each fixed column, and a water screen is arranged between the two telescopic rods. A water screen storage groove is formed in the ground between the two fixed columns, and the water screen storage groove extends along the width direction of the garage entrance. A lifting mechanism is arranged at the top of each fixed column. The two lifting mechanisms are connected with a lifting rod, one end of the lifting rod is connected with the water screen, and the other end of the water screen is fixed to the bottom of the water screen storage groove. The lifting mechanism can drive the lifting rod to move up and down, so that the water screen is unfolded or folded. The application is high in flood control efficiency and can effectively prevent accumulated water from overflowing.

The invention belongs to the technical field of air conditioner drainage protection, and particularly relates to an anti-backflow device used for connecting air conditioner condensate water drainage to a building drainage system, the anti-backflow device comprises an integrated shell, the top and the bottom of the integrated shell are provided with a water inlet and a water outlet respectively, and a partition plate is transversely arranged in the integrated shell; a partition plate is arranged in the integrated shell, the partition plate divides the integrated shell into a water seal cavity and a buffer cavity, the water seal cavity is located above the buffer cavity, a first vertical plate is arranged in the water seal cavity and fixedly connected to the upper portion of the partition plate, an overflowing gap is reserved between the first vertical plate and the top of the integrated shell, and the first vertical plate divides the water seal cavity into a water storage area and a drainage area. A second vertical plate is arranged in the water storage area and fixedly connected to the top of the integrated shell. No matter the air conditioner stops for a long time, the pressure of the building drainage system fluctuates or the building drainage system is blocked, effective response can be made, and it is ensured that the backflow prevention function is continuous and effective.

The utility model relates to the technical field of fire-fighting spray heads, and discloses a high-precision fire-fighting spray head with a built-in anti-backflow device, which comprises a disc top, the bottom of the disc top is fixedly connected with a fixed frame, the inside of the fixed frame is fixedly connected with a motor, the output end of the motor is fixedly connected with a bent handle, and the bent handle is fixedly connected with the anti-backflow device. A water pump is rotationally connected into the bent handle, and angle adjusting assemblies are arranged on the two sides of the fixing frame. The angle adjusting assembly comprises an L-shaped rod and a supporting column, one end of the L-shaped rod is fixedly connected to the outer wall of the fixing frame, and the supporting column is rotationally connected to the interior of the L-shaped rod. According to the utility model, the output end of the motor drives the bent handle to rotate, and meanwhile, the water pump rotates to drive the hollow frame and the supporting rod to rotate in the L-shaped rod, so that the effect of performing rotary spraying on the spraying head is achieved, the problem that when a fire disaster occurs, the fixed spraying head is difficult to extinguish a larger area is solved, and the applicability of the fire-fighting spraying head is improved.

The utility model discloses a rainwater backflow prevention device for rock wool fireproof ocean platform container, relates to ocean platform container technical field. The rainwater backflow prevention device for rock wool fireproof ocean platform container, including container house, the bottom intercommunication of container house is provided with the water pipe, the bottom fixedly connected with U shape water seal pipe of water pipe, the utility model discloses when the external rainwater first enters the closed box inner chamber through the flow guide pipe, the rainwater first accumulates in the slide plate bottom area, along with the water level continuously rising, the float ring of setting in the periphery of drain pipe because of the liquid buoyancy effect and follow the floating, and drive the slide plate along the I -shaped guide rail and slide up, the rising of slide plate further drives the closure plate, makes it gradually close and finally completely covers U shape water seal pipe communication mouth, at this moment, the aperture of U shape water seal pipe is blocked, effectively blocked the possibility that external rainwater through drain pipe reverse flow into container inside.

The utility model relates to the technical field of sterilization machines, and discloses a low-temperature backflow prevention device for UHT high-temperature sterilization, which comprises an outer frame, a material mixing frame is arranged above the outer frame, and a motor is fixedly mounted on the inclined side surface of the material mixing frame. Through cooperative use of a stop block and a manual valve and cooperative use of the stop block and a pump body, when the sterilization temperature cannot reach the sterilization temperature in the early stage and the sterilization effect is not ideal, the pump body can be controlled to work through a controller, and the interior of the sterilization tank is pressurized through the pump body; the material flow in the sterilization tank flows into the backflow pipe through the second communicating pipe again, then the manual valve is manually rotated, the stop block is rotated to be opened and closed, and then the material flow can smoothly flow into the first communicating pipe through the backflow pipe, flow into the pump from the first communicating pipe and flow back into the temporary storage tank again, so that the material flow is temporarily stored; and the situation that part of materials cannot reach the sterilization expectation and can only serve as waste materials to be treated, and waste is caused is avoided.

The utility model discloses a backflow prevention device for an engine oil pump, and belongs to the technical field of engine oil pumps. The device mainly comprises a shell, oil inlet pipes are fixedly connected to the two sides of the shell, an anti-backflow cavity is formed in the inner side of the shell, one end of each oil inlet pipe communicates with the anti-backflow cavity, a connecting flange plate is fixedly installed at the front end of each oil inlet pipe, and an anti-backflow assembly is arranged in the anti-backflow cavity. The connecting plate is fixedly installed at the joint of the oil inlet pipe and the backflow prevention cavity, a telescopic air cylinder is fixedly installed at the front end of the connecting plate, a piston rod is fixedly connected to the front end of the telescopic air cylinder, a backflow prevention plug is fixedly connected to the front end of the piston rod, and the backflow prevention plug is slidably connected with the oil inlet pipe. Telescopic sliding rods are fixedly installed on the two sides of the piston rod, and a rubber layer is fixedly installed at the front end of the backflow prevention plug. According to the backflow prevention device for the engine oil pump, the oil return impact force is reduced, the load of the oil pump is reduced, and the service life of the oil pump is prolonged.

To provide a pipe joint having a backflow prevention part.SOLUTION: A pipe joint according to the present invention includes a joint body (10) formed in a cylindrical shape, a lateral pipe connection portion (14) having an end portion connected to a side surface of the joint body (10) and an opening formed at the end portion and communicating with an inside of the joint body, a bush (25) fitted to the lateral pipe connection portion (14) and to which a lateral pipe is connected, and a backflow prevention portion (29) protruding from an inner peripheral surface of the joint body (10) toward an inside of the joint body (10) and formed in the bush (25).SELECTED DRAWING: Figure 1

Title: Hydraulic Air Backflow Prevention System The invention relates to a hydraulic air backflow prevention system, comprising: - a water collection tank (100); - a water outlet (2); - a hydraulic backflow prevention device (3) connecting the collection tank (100) to the water outlet (2), the hydraulic backflow prevention device (3) comprising a float (31) and a water collection bowl (32) incorporating a cage (4) within which the float (31) is movable according to a water level (NE) in the collection bowl (32). Figure for the abstract: Fig. 1

A sink dishwasher with drying and disinfecting functions comprises a sink, a cover plate and a drying and disinfecting device, and the sink comprises an annular edge plate, a lower air inlet hole formed in a rear wall plate, an upper exhaust pressure relief hole formed in the rear wall plate and an exhaust hole set formed in the annular edge plate; the exhaust pressure relief hole is communicated with the exhaust hole group; the drying and disinfecting device comprises a shell with a front opening, a fan, an air heating device, a flow guide pipe, a negative ion generator and an air guide part, the negative ion generator comprises a circuit board, a high-voltage power supply and a discharge electrode, the fan, the air heating device and the flow guide pipe are sequentially communicated and arranged in the shell, the flow guide pipe extends out of the shell, and the discharge electrode is arranged in the flow guide pipe; the air guide piece is communicated with the flow guide pipe; the shell and the rear wall plate are buckled and fixed, and the air guide piece is communicated with the air inlet hole; and the air inlet end of the air guide piece is provided with an anti-backflow device. By arranging the anti-backflow device in the air guide piece, steam or water flow is prevented from entering the drying and disinfecting device when the sink dishwasher works, and potential safety hazards are eliminated.

The utility model relates to the field of medical equipment, in particular to a water backflow prevention device outside a foramen intervertebrale mirror, which comprises a water retaining piece, an upper water retaining piece and a lower water retaining piece, the upper water retaining piece and the lower water retaining piece are both in a super-semicircular ring shape and are both positioned on the circumferential outer wall of a handle of a target foramen intervertebrale mirror, and the upper water retaining piece and the lower water retaining piece are arranged on the circumferential outer wall of the handle of the target foramen intervertebrale mirror. The projections of the upper water retaining piece and the lower water retaining piece on the handle diameter plane of the target intervertebral foramen mirror are circular, and water guiding grooves are formed in the top ends of the upper water retaining piece and the lower water retaining piece. The device has the effect of reducing potential safety hazards of an operation.

The present invention provides a commercial floor-cleaning robot disinfection box spray pipe anti-backflow water device, comprising a robot body, characterized in that it also includes an anti-backflow unit, a conveying unit, and a storage unit; the anti-backflow unit is arranged above the robot body to prevent the disinfectant from flowing back; the conveying unit is arranged behind the anti-backflow unit and is connected to the anti-backflow unit, and is used to convey liquid to the anti-backflow unit; the storage unit is arranged behind the robot body and is connected to the conveying unit for storing liquid. By adding a liquid storage tank, the present invention effectively allows the disinfectant remaining in the conveying pipe and the spray port to flow back into the liquid storage tank when the upper cover of the machine is open. This not only prevents the disinfectant from flowing into the interior of the machine and onto the operating display screen, making it difficult to clean and corroding parts, but also refluxes the disinfectant through the reflux device, thereby improving the utilization rate of the disinfectant and reducing the cost of using the machine.

The invention belongs to the technical field of control equipment, and discloses a power plant river water backflow prevention device which comprises a valve body and further comprises an adjusting mechanism arranged on the outer wall of the valve body; the number of the connecting mechanisms is two, one connecting mechanism is arranged on the outer wall of the adjusting mechanism, and the other connecting mechanism is arranged on the outer wall of the valve body; the valve element is arranged in the inner wall of the valve body through a fixing mechanism, and the outer wall of the connecting plate is slidably connected with a sliding block; the adjusting mechanism comprises an adjusting channel; wherein the connecting mechanism comprises a connecting plate; through cooperation of the connecting plate, the sliding block and other structures, the positions of the bolt holes in the sliding block are adjusted, the device and an external pipeline can be connected and fixed through the positioning bolts, and therefore when the positions of the flange bolt holes of the external pipeline are different, adjustment and installation can be conducted through the connecting mechanism, and adaptability is high.

The embodiment of the utility model provides a management device for rocket propellant supply control, and belongs to the field of rocket propellant supply control. The management device used for rocket propellant supply control comprises a partition plate used for dividing a propellant storage box into two parts, and further comprises a plurality of straight-through communicating pipes arranged on the partition plate at intervals; and the anti-reflux device is arranged at one end, far away from the partition plate, of each straight-through communicating pipe. According to the management device, the situation that the pressure of the storage tank is reduced due to the fact that the cryogenic propellant is violently mixed with the main body pressurized gas of the propellant storage tank is effectively avoided, and the configuration requirement of a pressure supplementing gas cylinder is reduced.

The utility model relates to the technical field of cleaning equipment, in particular to a floor brush mechanism, cleaning equipment and a cleaning system. The floor brush mechanism comprises a water tank assembly and a rolling brush assembly. The water tank assembly comprises a sewage tank which comprises a tank body. An inner cavity of the box body is divided into a first cavity and a second cavity by the dry-wet separation part, the first cavity is located on the upper side of the dry-wet separation part, the second cavity is located on the lower side of the dry-wet separation part, the dry-wet separation part is provided with a water outlet communicating with the first cavity and the second cavity, a fence is arranged around the water outlet, and the fence is provided with an overflowing opening communicating with the two sides of the fence; the backflow prevention device is arranged at the water outlet and is constructed to enable the sewage in the first chamber to flow to the second chamber in a one-way manner; the rolling brush assembly is arranged on the side, in the first direction, of the sewage tank and is constructed to drive sewage to flow into the first cavity through rotation of the rolling brush assembly. According to the floor brush mechanism, dry and wet separation of sewage can be achieved, sewage recycling is smoother, and sewage backflow and overflow are prevented.

An air conditioner pipeline anti-backflow device comprises a prefabricated building block and an embedded pipeline obliquely embedded in the prefabricated building block, and an air conditioner pipeline can penetrate through the embedded pipeline. The two ends of the pre-buried pipeline penetrate out of the two sides of the prefabricated building block correspondingly, the first end of the pre-buried pipeline is higher than the second end of the pre-buried pipeline, and an elastic tightening ring is arranged at the second end and used for tightening the outer wall of the air conditioner pipeline. An elastic rubber ring is further arranged in the embedded pipeline and used for sealing a gap between the outer wall of the air conditioner pipeline and the inner wall of the embedded pipeline. And by prefabricating the air conditioner pipeline anti-backflow device, time and labor are saved during wall construction, and later manual drilling is not needed. And the pre-buried pipeline is obliquely buried, so that condensate water of the air conditioner pipeline can be effectively prevented from flowing back into a room. And an elastic tightening ring is arranged, so that the embedded pipeline can be closed. And the elastic rubber ring is arranged in the pre-buried pipeline, so that sealing between the air conditioner pipeline and the pre-buried pipeline can be realized, and condensate water, external impurities and the like are effectively prevented from invading an indoor space.

The utility model discloses an anti-backflow device for an underground structure, which comprises a water level floating detection valve, an intercepting ditch is arranged at the upper end of a ramp plate of the underground structure, and the water level floating detection valve is arranged at the top of the intercepting ditch; the waterproof roller shutter comprises guide rails and a shutter plate, the ramp plate is provided with a strip-shaped through hole, the strip-shaped through hole is formed in the width direction of the ramp plate, the upper end of the shutter plate is movably inserted into the through hole, the guide rails are laid on retaining walls on the two opposite sides of the ramp plate respectively, and the two guide rails are oppositely provided with vertically-arranged guide grooves. The two opposite sides of the curtain plate are arranged in the guide grooves of the two guide rails in a sliding mode. The driving reel is rotatably mounted between the two retaining walls, and a lifting rope is connected between the driving reel and the upper end of the curtain plate; and the controller is connected to the water level floating detection valve and the driving reel. The underground structure anti-backflow device solves the problems that an existing underground structure anti-backflow method is intelligent and slow in response speed.

The present application relates to the technical fields of building engineering pipeline, and specifically relates to a backflow prevention device for a sewage pipe, which comprises a sewage pipe, a straight pipe penetrating through the sewage pipe, a mounting hole being formed in the sidewall of the straight pipe, an air bag being mounted on the upper portion of the mounting hole, the top end of the air bag being fixedly connected with the upper portion of the mounting hole, a floating ball switch being arranged in the annular space formed between the straight pipe and the sewage pipe, an air inlet pipe and an air outlet pipe being communicated with the upper portion of the air bag, an air pump being communicated with the other end of the air inlet pipe, the air pump and the other end of the air outlet pipe both being located outside the sewage pipe, an air inlet valve being mounted on the air inlet pipe, an air outlet valve being mounted on the air outlet pipe, a control panel being mounted on an operation panel, a green indicator lamp, a red indicator lamp and a starting switch being mounted on the control panel, the floating ball switch, the air pump, the green indicator lamp, the red indicator lamp, the air inlet valve and the air outlet valve all being electrically connected with the control panel. The backflow prevention device for a sewage pipe solves the problem of backflow of the existing sewage pipe and is suitable for the pipeline for conveying or discharging sewage.

To provide a backflow prevention device that suppresses the backflow of molten resin while preventing galling of a check ring.SOLUTION: A backflow prevention device of the present invention comprises: a check head fixed to the tip of the screw; a check ring fitted onto the check head so as to be slidable between a forward limit that allows the passage of molten resin and a backward limit that prevents the passage of molten resin; and a check sheet fixed by extrapolation to the check head at a position where it abuts against the check ring at the backward limit. The check ring has a cylindrical portion with a communication passage formed between itself and the check head for passing molten resin, and a locking claw that protrudes from the cylindrical portion in the axial direction of the screw and is locked to the check head. The axial length of the cylindrical portion is shorter than that of the check sheet.SELECTED DRAWING: Figure 4