RU2262913C1 - Apparatus for making cyclic compression - Google Patents

Abstract

FIELD: medical engineering.

SUBSTANCE: device has electronic control unit, mechanism for feeding fresh air, alternating voltage source, transformer, device for releasing pressure, pressure transducer, safety valve, buffer capacity, throttle, stabilizing capacity, receiver, T-branch and inflatable articles for being put-on over patient extremities. The apparatus operates by periodically pressurizing the inflatable articles during treatment session. The apparatus operates in cyclic mode. Given pressure level is supported within the first half of every cycle and pressure close to atmospheric one is supported within the second half. Session and cycle duration, and pressure level are controlled with switches. Protection against pressure violating permissible threshold is provided with emergency valve introduced into the design.

EFFECT: wide range of functional applications; high security level.

12 dwg

Description

The invention relates to medical equipment, in particular, for the treatment of edema caused by venous insufficiency and imbalance in the microcirculation, by periodically acting in the form of pressure on the patient's limbs.

A device is known (No. A99106785 / 14 dated 09/12/97, IPC 7 A 61 H 7/00, 39/04, BIPM No. 15, 2001) "System and method for applying a variable load to the human body." Also known device (No. C2 2161474 from 07.16.96, IPC 7 A 61 H 9/00, BIPM No. 1, 2001) "Pneumatic massage suit".

The disadvantage of these known devices is the lack of a mechanism for emergency automatic pressure relief in the event of a malfunction, which reduces the safety of their use.

A chest compression device is known, selected as a prototype (PCT patent (WO); International application No. 91/11166 dated January 30, 1990; publication 08.08.91 No. 18; РЖ "Inventions of the world", art.7 No. 14 - 1992 .) containing an AC motor that controls the “blower” to pump pressure into the inflatable product, an AC motor that controls the blower to pump pressure from the inflatable product; a rotary valve that rotates under the action of a DC motor with a frequency determined by the motor controller, which includes a manual control for measuring the speed of rotation of the motor.

When the rotary valve is rotated due to its design, either the channel for pumping air or the channel for pumping pressure is cyclically connected to the inflatable product, as a result of which the pressure in the vest cavity changes cyclically with the speed of rotation of the rotary valve. The device also includes manual air flow control elements: a solenoid valve, flow control valves from the side of positive and negative air flows.

The disadvantages of this device are the lack of automation, expressed in the need for patient participation in the operation of the device with the constant involvement of at least one hand, as well as insufficient safety of the device due to the lack of an emergency pressure relief valve.

The aim of the present invention is to increase security and expand functionality.

Thromboembolic complications in recent years have become much more frequent and occupy one of the first places among complications of the postoperative period. The risk of thrombosis is great in abdominal, orthopedic and urological surgery, especially in the elderly. According to Torburn (The Hague, 1992), deep venous thromboses detected during phlebographic studies are observed in 67% of the operated. The reason is a significant deterioration in venous blood flow in the lower extremities during operations and in the postoperative period.

The cyclic compression device can be used to prevent thromboembolic complications, intra - and after surgical complications. In addition, the device can be successfully used to treat edema caused by venous and lymphatic insufficiency, to reduce tumors after fractures, and to prevent varicose veins in pregnant women.

Functional diagram of the apparatus of cyclic compression is presented in figure 1.

1 - electronic control unit

2 - mechanism for supplying compressed air (compressor)

3 - pressure sensor

4 - safety valve

5 - buffer capacity

6 - throttle

7 - pressure relief device (electro-pneumatic valve)

8 - stabilizing capacity

9 - receiver

10 - inflatable product - stocking

10 '- inflatable product - femoral cuff

10 '' - inflatable product - sleeve

11 - AC voltage source ~ 220 V

12 - transformer

13 - tee

14 - the first output of the stabilizing tank 8

15 - the second output of the stabilizing tank 8

16 - the third output of the stabilizing tank 8

17 - the fourth output of the stabilizing tank 8

18 - input stabilizing capacity 8

The controls and indications of the apparatus are presented in figure 2.

20 - SESSION indicator

21 - PRESSURE indicator

22 - session setting switch

23 - cycle setting switch

24 - pressure setting switch

25 - START button

26 - STOP button

The operation of the apparatus is to periodically pressurize the inflatable parts for a certain time, called the session time. During the session, the device operates cyclically. In each cycle, during its first half, the pressure rises to a predetermined value, and then the pressure is maintained at the achieved level until the beginning of the second half of the cycle. If the pressure reaches a predetermined one, and then, due to a natural air leak, decreases to a certain threshold, which is determined by the accuracy of maintaining the pressure, the pumping process begins to a predetermined value. During the second half of the cycle, the pressure drops to a value of (5-8) mm Hg. Art. and keeps at that level.

The duration of the session and cycle, as well as the pressure value, is set using the corresponding switches 22, 23 and 24.

A session begins by pressing the START 25 button, ends automatically after the appropriate time has elapsed or ahead of schedule by pressing the STOP 26 button, as well as when the power is lost.

In all cases, the apparatus returns to its original state with pressure relief from the limbs.

The mechanism for supplying compressed air (compressor) 2, which includes an AC motor, is powered by ~ 220 V, 50 Hz. According to the "Start" signal from button 25, the electronic control unit 1 generates a control signal, by which the compressor 2 is turned on, and it starts to increase the pressure in the pneumatic system. When the pressure reaches a predetermined level from the electronic control unit 1, a control signal arrives to turn off the mechanism for supplying compressed air (compressor) 2, and it turns off. When the pressure drops due to natural leaks below a certain level under the influence of control signals, the compressor 2 briefly turns on and pumps up the pressure to the previous value.

The electronic control unit 1 uses, as a supply, the voltage of the secondary windings of the transformer 12 and serves to generate electrical signals that control the operation of the cyclic compression apparatus.

The electronic control unit 1 receives information from switches 22, 23, 24 and, in accordance with the set values of the session time and cycle, generates the corresponding time intervals, and also analyzes the current pressure level and compares it with the set.

By pressing the START 25 button, the electronic control unit 1 lights up the SEANCE 20 indicator, gives a control signal to start, and when the pressure reaches the set level, it generates a signal to turn off the mechanism for supplying compressed air (compressor) 2, then, during the first half of the cycle, controls compressor 2 to maintain pressure at a predetermined level.

At the end of the first half of the cycle, the electronic control unit 1 prohibits the inclusion of compressor 2 and keeps the electromagnetic valve 7 open until the pressure in the pneumatic system of the apparatus drops to a level of (5-8) mm Hg. Art. (residual pressure). In this state, the cyclic compression apparatus is all the time remaining until the end of the cycle. The process flow chart is shown in FIG. 3.

At that moment, when the electronic control unit 1 has finished counting the time of the operation session, control actions are formed to turn off the compressor 2 and open the electromagnetic valve 7, which will result in a decrease in the pressure level in the pneumatic system (including in inflatable products) to atmospheric pressure, the SEANCE indicator disconnected. During the session, the PRESSURE indicator lights up for the time during which the pressure in the pneumatic system is equal to the set value. Pressing the STOP 26 button leads to the same result as the end of the session time.

The electromagnetic valve 7, as mentioned above, is controlled by the electronic control unit 1. The valve is energized and holds the air pressure in the pneumatic system, relieving the voltage from the valve leads to its opening and pressure relief.

Pressure sensor 3, with voltage output, has two pneumatic inputs. One of them is connected by a tube to the pneumatic system of the apparatus, and the other is open for access to atmospheric air. Sensor 3 determines the differential pressure of the inputs, i.e. its readings are independent of atmospheric pressure.

The electronic control unit 1 receives from the sensor 3 information about the current pressure in the pneumatic system and uses it to compare with a given level and lower acceptable pressure limit during pumping and pumping, as well as with a residual pressure (5-8) mm Hg. Art. when air is released through the electromagnetic valve 7 during the second half of each cycle.

The buffer tank 5, the stabilizing tank 8 and the receiver 9 are air storage devices that smooth the process, provide a smooth change in pressure without surges.

They are made in the form of a parallelepiped. The walls are made of metal and interconnected by screws. To achieve tightness, rubber gaskets are used, the screws are filled with sealant.

The buffer tank 5 has three pneumatic inputs, the stabilizing tank 8 - five pneumatic inputs and the receiver 9 - two pneumatic inputs.

At the input of the pressure sensor 3, a throttle 6 is installed, which is a metal insert with a thread placed in the tube. With sharp changes in pressure, air portions collide with the end face of the throttle 6 and flow around it. Thus, the throttle protects the pressure sensor 3 from sudden blows of air. The safety valve 4 is not controlled by the electronic control unit 1. It is used to relieve pressure in the pneumatic system in the event of emergency situations, when the pressure due to a malfunction is pumped above the maximum regulated value. The valve is adjusted so that it opens automatically at a value of 160 mmHg. Art. and close at 110 mm Hg. Art. Thus, in the event of a malfunction, the pressure in the pneumatic system of the apparatus (and therefore in inflatable products) cannot exceed the response pressure of the safety valve 4.

Inflatable products: stocking 10, femoral cuff 10 'and sleeve 10' 'can be connected to the cyclic compression apparatus in any combination and all at the same time depending on the need. They are worn on the limbs of the patient. Inflatable products consist of power and airtight shells. The power shell of the product is a cover made of oil and petrol resistant fabric. The inner layer, as less loaded, is made of thinner fabric. Inside the power cover there is a pressurized shell - a pneumatic chamber made of airtight rubberized fabric. Each inflatable product has two positions for adjusting to the circumferential size of the patient's limbs. For this purpose, detachable fasteners are sewn on the outer layer of the power cover - zippers, the locking part of which can be connected to each of the two mating parts.

The femoral cuff is designed to increase, if necessary, the length of the stocking.

Inflatable products provide uniform pressure on the surface of the patient's limbs. Each product has a fitting for connecting the connecting tubes.

The functional diagram of the control unit 1 is shown in FIGS. 4-9 (communications in the circuit terminated on one sheet and continued on another sheet are indicated by the same number on both sheets).

When you press the START 25 button on the front panel of the device, a logical "1" is set on the direct output of the SEANCE 27 trigger (Fig. 5), made on two valves of the aircraft microcircuit. The trigger is reset by pressing the STOP 26 button and by the RESET signal generated at the end of the set session time by the generator 115 at terminal 28 (Fig. 7).

In the presence of the SEANCE signal, a cyclic rise in pressure to a predetermined value occurs, and then a reset to the level of (5-8) mm Hg. When the signal is removed, the pressure is completely relieved, to atmospheric level. The state of the trigger SEANCE 27 using a circuit consisting of resistors 33, 35 and transistor 34, is displayed on the LED SEANCE 20 (figure 5).

Resistors 31, 32 are used to maintain the logic level 1 at the inputs of the trigger 27 with the buttons 25 and 26 open.

To measure the pressure in the pneumatic system, a 3 MPX5050 pressure sensor from MOTOROLA with a voltage output is used. The pressure range from 0 to 50 kPa corresponds to an output voltage of 0.2 to 4.7 V, which is supplied to the input of the voltage / frequency converter 36 AD654 of ANALOG DEVICES. The output signal of the converter in the form of a frequency is supplied to the input of the microcircuit 37 (Fig. 6) (KR512PS10), which in this case is a frequency divider with a division ratio of 6144. The output frequency of the microcircuit 37, therefore, depends on the pressure in the pneumatic system and is output to the comparison circuit for comparison with the setpoint frequency.

The setpoint circuit includes microcircuits 38 (Fig. 8) (KR512PS10), 39, 40 (K561KT3), 41 (LE5), a capacitor 42, resistors 43-60, and a pressure reference switch 24, which uses an 8-position wrench switch 2 directions (i.e. 2 contacts are closed at the same time).

Correspondence of the position of the pressure reference switch to 24 numbers of closed contacts:

30 mmHg - 63, 73;

40 mmHg - 64, 74;

50 mmHg - 65, 75;

60 mmHg - 66, 76;

70 mmHg - 67, 77;

80 mmHg Art. - 68, 78;

90 mmHg - 69, 79;

100 mmHg - 70, 80.

Chip 38 in this application is a generator with a division coefficient of 6144. The input frequency generated by the chip depends on the capacitance of the capacitor 42 and the total value of the resistors connected between terminals 61 and 62. The microcircuits 39, 40 play the role of switches connecting one of the three resistor circuits between the findings of 61 and 62 of the generator 38. The input frequency is divided by a factor of 6144 and fed to the comparison circuit.

At the beginning of each cycle, when pumped, a resistor 43-50 is connected via a switch "P <" through a switch 40 (Fig. 8), depending on the position of the pressure setting switch 24 on the device panel, these resistors are turned on in various combinations. Since a higher frequency value corresponds to a higher pressure value in the pneumatic system, and the generator 38 generates the frequency, the higher the lower the resistance in the circuit, the pressure is 100 mm Hg. corresponds to the inclusion in the circuit of one resistor 43, and a pressure of 30 mm Hg - a complete set of resistors 43-50.

When the pressure in the pneumatic system reaches a predetermined value, a control signal from a circuit consisting of microcircuits 171 and 172 (Fig. 9) is supplied to the switch 39. The same signal from the output of the microcircuit 172 through the resistor 173 opens the transistor 174, in the collector circuit of which a current begins to flow through the resistor 175 and the LED 176. Thus, the LED "Pressure" 176 lights up only at intervals when the pressure is near the set value set by the switch 24 (Fig. 8).

. Когда за счет естественных утечек давление достигает этой величины, то возникает сигнал "Р<" и к генератору 38 вновь подключаются только резисторы 43-50.When the pressure in the pneumatic system reaches a predetermined value, the signal "P>" to the output 62 of the microcircuit 38 (Fig. 8) through two parallel valves of the switch 39 is additionally connected to the resistor circuit 43-50 resistor circuit 51-58. Moreover, in accordance with the position of the pressure reference switch 24 on the apparatus panel, a set of resistors from the set of 51-58 is added to each set of resistors from the set of 43-50. Thus, the current pressure of the pneumatic system begins to be compared with a pressure level lower than the set point by a certain amount

. When the pressure reaches this value due to natural leaks, a signal "P <" appears and only resistors 43-50 are reconnected to the generator 38.

At the end of the half-cycle time, according to the "END" signal, a chain of resistors 59 and 60, which correspond to a low pressure level of 5-8 mm Hg, is connected to the output 62 of the generator 38 (Fig. 8). This residual pressure is necessary to accelerate the pumping process.

The comparison circuit is implemented on the logic elements 71, 72, 81, 82 (Fig.6), the shifting register 83, the triggers 84-87, as well as the resistors 88, 89 and the capacitors 90, 91. Signal generation in the comparison circuit for different ratios of the sensor frequencies and the setpoint shown in Fig.10-12.

The output frequency of the setpoint loop is removed from the output 92 of the generator 38 (Fig. 8), and half the period of the output signal with a logic level of "0" passes completely, and two pulses are formed on the positive edge of the triggers 85, 86 (Fig. 6) (from the output 93 - negative polarity, from the output 94 - positive), according to the second of which the generators 37 (Fig. 6) and 38 (Fig. 8) are reset, after which a new frequency truncated by zeroing begins. Comparison occurs once on each period of the setpoint frequency.

At the beginning of each cycle of the apparatus, the frequency of the sensor circuit is less than the frequency of the setpoint (see Fig. 10), since the pressure in the pneumatic system has not yet reached the setpoint. In this case, pulses are generated at the outputs 97 and 99 (Fig. 6), which write a logical “1” and a logical “0” to the first bit of the first and second shift registers 83, respectively. After quadruple confirmation, a logical “1” will appear at the output 101 ( the output of the fourth bit of the first shift register), and the logical "0" at the output 102 (the output of the fourth bit of the second shift register), the signal "P <" is generated at the direct output of the trigger 87. This means that the pressure in the pneumatic system is less than the set value.

With a further increase in pressure, the frequencies of the sensor and setpoint loops will become close (see Fig. 11). The shift registers 83 (Fig.6) will be accessed twice during each comparison cycle: for the first time, the logical “1” will be written to the least significant bit of one of the registers, the other register will be reset, and the second time, vice versa. In this case, the state of the trigger 87 will not change, which means that the signal "P <" will still remain on the direct output of the trigger 87.

When the frequency of the sensor circuit exceeds the frequency of the setpoint loop (see FIG. 12), after four comparison cycles, logic “1” will appear at the output 102 (the output of the fourth digit of the second shift register), and at the output 101 (the output of the fourth discharge of the first shift register) - logical "0", at the inverse output of the trigger 87, a signal "P>" is generated (Fig.6). This means that the pressure in the system does not need to be increased anymore.

With the beginning of each cycle, the mechanism for supplying compressed air (compressor) 2 starts and stops when the signals "P>" or "END" appear, so the pressure rises during pumping and pumping when "P>" is absent. In the intervals between pumpings, the compressor does not work due to the presence of the "P>" signal, and at the end of the first half of the cycle, due to the "END" signal, the "P>" and "END" signals are inputted to the chip 166 on the "OR" (Fig. 7). If there is a high level of one of these signals, the base of the transistor 168 receives a low signal level through the resistor 167 (Fig. 4), and the transistor 168 closes, the current does not flow along the control circuit of the opto-thyristors 169 and 170, the opto-thyristors 169, 170 are closed, and the compressor 2 stops .

и открывается в момент окончания первой половины цикла (под давлением). Давление в пневмосистеме начинает падать и уменьшается до тех пор, пока не станет равно 5-8 мм рт.ст. После этого сигнал "Р>" снимается и клапан 7 закрывается. Клапан 7 закрыт тогда, когда через него течет ток.The operation of the pressure relief device (electro-pneumatic valve) 7 is controlled by a circuit consisting of microcircuits 103-105, transistors 106-108, resistors 109-112, capacitor 113 and diode 114 (Fig. 9). At the beginning of each cycle, valve 7 is closed by a signal

and opens at the end of the first half of the cycle (under pressure). The pressure in the pneumatic system begins to fall and decreases until it becomes equal to 5-8 mm Hg. After that, the signal "P>" is removed and the valve 7 is closed. Valve 7 is closed when current flows through it.

At the end of the session and when the power is turned off, the electro-pneumatic valve 7 opens, the pressure in the pneumatic system of the device is released to atmospheric. The pressure relief device 7 has a large inrush current, to ensure that at the moment the current flows through the trigger 105, powerful transistors 108 and 107 open, open only for a short time, determined by the value of the capacitor 113 and resistor 111. Subsequently, the current flows through the transistor 106.

The session time reference circuit is made on a chip 115 (КР512ПС10) (Fig. 7), a capacitor 116, resistors 117-128 and a session setting switch 22. The cycle time reference circuit is constructed similarly and consists of a chip 141 (Fig. 5), a capacitor 142, resistors 143-152 and a cycle reference switch 23.

Chips 115 and 141 are frequency generators with a given division ratio. The frequency generated by the generators is determined by the value of the capacitance connected between the terminals G and IG, as well as the resistance between the terminals IG and OG. Using the switches for setting the cycle 23 and session 22 on the front panel of the device, you can set different values of the cycle and session, which correspond to different combinations of resistors from sets 143-152 and 117-128, and therefore different input frequencies of the generators 141 and 115. Division factor microcircuit 141 is 131072, microcircuit 115-3932160.

As switches for setting the session 22 and cycle 23, the dial switches are used for 12 and 10 positions, respectively.

Correspondence of the position of the session setting switch to 22 numbers of closed contacts:

10 min - 129;

20 min - 130;

30 min - 131;

40 min - 132;

50 min - 133;

60 minutes - 134;

70 min - 135;

80 min - 136;

90 minutes - 137;

100 min - 138;

110 minutes - 139;

120 minutes - 140.

Correspondence of the position of the cycle setting switch to 23 numbers of closed contacts:

2 minutes - 153;

3 minutes - 154;

4 min - 155;

6 minutes - 156;

8 minutes - 157;

10 minutes - 158;

12 minutes - 159;

16 min - 160;

20 minutes - 161;

30 min - 162.

Until the device is started by the START button 25, the generators 141 and 115 are reset to zero at the zeroing inputs by a high-level signal from the inverse output of trigger 163. When the trigger is applied, the SEANCE signal appears, the zeroing is removed from the generators and they begin to generate an input frequency that is shared with the above division ratios.

(вывод 164), а во второй половине - сигнал "END" (вывод 165). В выходной цепи генератора 115 (фиг.7) половина периода выходной частоты соответствует установленному времени сеанса. С инверсного выхода 28 в течение времени сеанса поступает логическая "1" на вход сброса триггера СЕАНС, реализованного на микросхеме 27 (фиг.5), по окончании времени сеанса с выхода 28 подается логический "0" на триггер СЕАНС 27 и сбрасывает его.In the output circuit of the generator 141 (FIG. 5), the frequency period corresponds to the set cycle time. During the first half of the period, a signal is generated

(pin 164), and in the second half - the signal "END" (pin 165). In the output circuit of the generator 115 (Fig. 7), half the period of the output frequency corresponds to the set session time. From the inverse output 28, during the session time, a logical "1" is input to the reset input of the SEANCE trigger implemented on the chip 27 (Fig. 5), at the end of the session time, a logical "0" is supplied to the CEANCE 27 trigger and resets it.

The voltage removed from the first secondary winding of the transformer 12 passes through a rectifier 29 and a stabilizer 30 (figure 4) and serves to obtain a five-volt power supply of the logic elements of the electronic control unit 1.

Rectified rectifier 177 voltage of the second secondary winding is used to power the device to relieve pressure 7 (Fig.9).

The third secondary winding through the rectifier 178 and the stabilizer 179 feeds the control circuit of the opto-thyristors 169 and 170 (figure 4).

When using the apparatus of cyclic compression switches 22, 23 and 24 set the cycle time and session, as well as the pressure level. Then the patient puts on inflatable products on the limbs. At the same time, 2 patients can undergo the procedure. After that, it is enough to press the START 25 button and the device will cyclically with a period equal to the cycle time pressurize the inflatable products and release it to the level of (5-8) mm Hg. Art. The procedure ends automatically at the end of the session. The cyclic compression apparatus provides for setting the duration of the session from 10 minutes to 2 hours with a resolution of 10 minutes, the pressure from 30 to 100 mm RT. Art. with a discrete of 10 mm RT. Art. and finally, the cycle time is selected from a number of 2, 3, 4, 6, 8, 10, 12, 16, 20, and 30 minutes.

The procedure can be interrupted ahead of schedule by pressing the STOP 26 button. In any case, the end of the procedure is accompanied by a complete release of pressure from the patient's limbs. During the procedure, the patient (patients) should not perform any manipulations, since the device performs the specified operating mode automatically.

Thus, the claimed apparatus of cyclic compression meets the criteria of the invention of "Novelty."

1. The introduction of the electronic control unit 1 and controls 22-26 and displays 20, 21 allows the measurement of cycle time and session, measurement and comparison of the pressure in the pneumatic system with a given level and, as a result, makes it possible to automate the operation of the apparatus and completely eliminate interference with the patient.

2. The analysis of pressure in the pneumatic system of the device became possible thanks to the introduction of a pressure sensor.

3. To increase patient safety, an emergency valve (safety valve 4) was introduced, which automatically opens at a pressure of 160 mm Hg. Art. and prevents a further increase in pressure in the pneumatic system of the apparatus.

4. The introduction of two channels (due to the stabilizing capacity of 8 and tee 13) allows you to increase the return of the device and use it to treat two patients at the same time. For the lower limb, a stocking is provided in combination with the femoral cuff, attached to the first channel using a tee, for the upper limb - a sleeve attached to the second channel of the apparatus.

Claims (1)

A cyclic compression apparatus comprising a mechanism for supplying compressed air, an AC voltage source, a transformer, a pressure relief device, an inflatable product, characterized in that an electronic control unit, a pressure sensor, a safety valve, a buffer tank, a choke, a stabilizing tank are introduced into it, the receiver, the tee, and the inflatable product is made in the form of a stocking, femoral cuff and sleeve, while the sleeve is connected by a tube to the first output of the stabilizing tank, with the second output of which through the tee the stocking and the femoral cuff are dined, with the third output - the pneumatic inlet of the pressure relief device, with the input - the first pneumatic inlet of the buffer tank, with the fourth output - the receiver’s input, the output of which is connected to the first end of the throttle, the second end of which is connected to the pneumatic input of the pressure sensor, the output is the voltage of which is connected to the first output of the electronic control unit, the second and third outputs of which are connected to the first and second electrical inputs of the pressure relief device, the fourth output to the control input of the mechanism for compressed air supply, the fifth output - with the first output of the AC voltage source and with the first output of the transformer primary winding, the first, second, third, fourth, fourth, fifth and sixth power inputs - with the first and second outputs of the first, second and third secondary transformer windings, respectively , the second terminal of the primary winding of which is connected to the second terminal of the AC voltage source and to the power input of the mechanism for supplying compressed air, the pneumatic output of which is connected to the second pneumatic inlet of the buffer tank, tii pneumatic inlet which is connected to the safety valve.

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