The present invention relates to a high pressure safety hose designed for continuous monitoring of the integrity of the high pressure hose when in use, where the hose provides for pressure communication using hydraulic fluid between a pressure generating device and a user location, the safety hose includes a main hose that contains the hydraulic fluid, a secondary hose is arranged around the main hose, and a sealing connection between the main hose and the second hose at each end of the safety hose for the formation of a cavity between the hoses.

The invention relates in general to high-pressure hoses, and especially hydraulic hoses which can easily represent a danger to their surroundings if they are subject to burst during use. When conventional hydraulic hose burst, they can cause violent lashes and hit by standing personnel and inflict serious injury and mutilation. Another type of damage to these hoses are so called pinhole leakage that emits a thin jet with a high speed that can penetrate the skin of people who are close to the leakage. In order to improve safety around the mentioned conditions there is recent developed safety hoses of the initially mentioned type, accordingly an inner and an outer hose. But this is not sufficient. It will only delay the problem until the fracture occurs in the outer hose.

The present invention aims to prevent such injuries and stop the leakage before it will cause harm. It is therefore important to monitor and detect the early leakage, called sweating, in the main hose as soon as it has occurred and prevent it from evolving to a major problem. A further objective is be able to continue operation of the equipment that the hose serves until the operation can safely be stopped and the hose repaired or replaced.

This is achieved with a safety hose of the initially mentioned type which is characterized in that the cavity of the safety hose during operation is filled with air/inert gas continuously/regularly supplied to the cavity under predetermined pressure through an inlet valve and exits the cavity through an outlet valve, both valves being able to close the inlet (1 l)/outlet (12) respectively when a predetermined pressure is exceeded in the cavity, while there simultaneously are ongoing continuous/regular detection of possible contamination that may arise in the cavity by use of a probe, both situations provide a signal that said integrity is broken.

It will thus be understood that new and the fresh air/inert gas is continuously supplied to the cavity. If the smallest leakage/sweating of hydraulic fluid occurs from the hose and into the cavity, this will immediately contaminate the air/inert gas that is quickly detected by the mentioned probe. Then an alarm is set and the operator is notified that a leak has occurred. Such a type of leakage will normally take some time to develop before becoming dangerous. This will give the operator sufficient time to finish the operation, when the situation is such that it can not be immediately stopped, such like a hanging load in mid-air. Then it will be good to be able to set the load down safely before the operation is terminated and the pressure relieved.

In another more dramatic situation when the main hose burst completely and fills up the cavity with hydraulic fluid. Secondary hose is provided prerequisite of such a nature that it can withstand the same hydraulic pressure as the main hose. When this occurs the valve in the inlet valve will automatically close due to pressure increase in the cavity. The outlet valve will automatically close because of the increased pressure and flow with fluid from the cavity. Thus, the pressure builds up in the cavity and the hose will work as normal so that the aforementioned ongoing work may be terminated in a safe and secure manner.

Then one has achieved a double protection system that is able to handle both early leakage, like sweating, and sudden and uncontrolled bursts in the main hose.

Thus, in one implementation provided a safety hose of the aforementioned type where the discharge valve includes a flow valve in and of itself any suitable known type, where the flow valve is arranged so that the leakage from the hose into the cavity will close the flow valve for further discharge of the air/inert gas from the cavity, and the inlet valve includes a check valve in and of itself any suitable known type, which valve is so arranged that the leakage from the hose into the cavity will close the valve for further introduction of air/inert gas, thus increasing the pressure in supply line on the upstream side of the inlet valve at the predetermined pressure level, release the said signal. Typically, the air/inert gas will be sent through the hose at a pressure of for example 4 (0,8) bar. If the pressure rises to, for example 6 (1,1) bar on the said upstream side, a signal will notify that the integrity is broken.

An advantage would be to locate the probe for detection of contamination near the outlet valve.

As possible alternatives to the introduction of air/inert gas to said cavity by means of a compressor, pump, pressure tank or the like.

In one implementation the cavity can be filled with anti-collapse devices, such as a steel coil around the main hose.

If required, the safety hose can include at least one of the following sensor devices: pressure sensor, temperature sensor, humidity sensor and rupture sensor and its lines to the control unit.

In a special design where fire is a potential risk can the inert gas be CO ₂ .

In another implementation, or in combination with others, a pressure sensor can be connected to the main hose, where this includes a relief valve capable of regulating pressure in the main hose.

Other and additional objectives, features and advantages will appear from the following description of preferred designs of the invention, which is given for description purposes and provided in relation with the attached drawings, where:

Figure 1 shows the front elevation, partly in cross-section, of a safety hose with inlet and outlet valves according to the invention,

Figure 2 shows the front elevation, partly in cross-section of the safety hose, according to Figure 1 with the addition of an overpressure protection, Figure 3 shows the front elevation, partly in cross-section of the security line, according to Figure 1 with the addition of a protection against fire,

Figure 4 shows the front elevation, partly in cross-section of the safety hose, according to Figure 1 with the addition of an anti-collapse part, Figure 5 shows the front elevation, partly in cross-section of the safety hose, according to Figure 1 with all the options shown in fig. 1-4 integrated into one single unit, and Figure 6 shows a complete system for automatic monitoring of a safety hose according to the invention.

First, see figure 1 which shows the basic design of a safety hose 10 according to the invention. Safety hose 10 is constructed so that it includes a main hose 1 which comprises the hydraulic fluid that transfer pressure and a secondary hose 2 is arranged around the main hose 1. At each end of the safety hose 10 is a sealing connection between the main hose 1 and second hose 2 to form a cavity 5 between the main hose 1 and second hose 2. Each end is arranged on the adapters 6, 7, and the couplings 3, 4 for hydraulic connection to a pressure source (not shown) and pressure user (not shown). Further, the secondary hose 2 has an reinforcement 2a in each end which is shrunk on the flexible secondary hose 2. A safety hose 10 as described above are currently on the market and are qualified and certified for high pressure.

It is worth noting that the inner loop in the main hose 1, which comprises the hydraulic fluid and transfer the pressure, is running straight through the hose and coupling parts and are completely isolated from the cavity and the outer coupling parts.

Between each segment 6, 7 and connections 3, 4 an adapter 8, 9 is mounted for connecting a nipple N supply/execution of the air/inert gas. In one version is one nipple N combined with an integral inlet valve 20 that are in direct communication with the cavity 5 between the main hose 1 and second hose 2. Inlet valve 20 is the type of check valve and release air / gas through already at very moderate pressure. This should be understood that the adapters 8, 9 have cavities and channels that will continue throughout the segment 6, 7 and into the hose cavity 5. Thus ends the cavity 5 before the respective coupling parts 3, 4. Equivalent, the other nipple N combined with an integral outlet valve 30 which is also in direct communication with the cavity 5 between the main hose 1 and second hose 2. The drain valve 30 (excess flow valve/max flow control valve) is the type of flow valve that lets air / gas through at moderate pressure, but closes when the set pressure is exceeded. This can be a ball or poppet that is held away from his seat by a spring in a known way.

In continuation of the nipple N, i.e. downstream of the outlet valve is arranged an oil separator 31 of known type. Oil separators have a collecting tank 32, an outlet 12 and a probe 33 that can detect pollutants or hydraulic oil. The probe 33 can send a signal to control unit that pollution is detected

At the opposite end, i.e., upstream of the nipple N on the inlet valve is arranged an inlet chamber with an inlet 11 and a pressure sensor 23 that is able to record a rise in pressure in the inlet chamber, i.e. the pressure increase upstream of the valve 20.

The above described equipment shall maintain two alternative leakage scenarios. These will be described below.

New and fresh air/inert gas is continuously or at regular intervals, provided the cavity 5 when the safety hose 10 is in use. This can be done using a compressor, air pump, gas bottle or anything suitable. If the smallest leakage/sweating of hydraulic fluid from the main hose 1 and into the cavity 5, it will immediately contaminate the injected air / inert gas this will quickly be detected by the probe 33 of the oil separators 31. When this happens an alarm will notify the operator that the leak has occurred. Normally such type of leakage will take some time to develop into a serious situation. This will give the operator time to stop the operation when the situation is such that it can not be immediately shut down, such as a hanging load being moved. Then it will be good to be able to set the load down safely before the operation is stopped and the pressure relieved. Another situation could be that the main hose 1 burst completely and immediately fills up the cavity 5 with hydraulic fluids. Secondary hose 2 is provided respectively of such a nature that it can withstand the same hydraulic pressure as the main hose 1. Once this occurs the valve 20 in the inlet valve is automatically closed because of pressure increase in cavity 5. Flow valve 30 in the outlet valve will also automatically close because of the increased pressure and fluid flow in the cavity 5. Thus, the pressure builds up in the cavity 5 and the safety hose 10 will work almost as normal so that the aforementioned ongoing work may be shut down in a safe and satisfactory manner.

When the valve 20 closes the pressure in the inlet 11, i.e. the inlet chamber, will rise and this will be detected by pressure sensor 23. The sensor will send a signal to the operator who will realize that a leak has occurred.

Figure 2 shows the same safety hose 10 as in Figure I ₅ but with a device functioning as an overpressure protection. The facility consists of a relief valve 61 that is attached to the safety hose 10. A connection pipe 10 is connected between one adapter 9 and the relief valve 61. This can be used if you want to lower the pressure in the main channel for hydraulic fluid. The piston in the relief valve 61 provides the opening / closing of a seat valve in the pressure relief channel 62 that directly relieves the pressure in the main channel. A multifunction sensor is mounted in the adapter 9.

Figure 3 shows the same safety hose 10 as in Figure 1, but with a facility functioning as a fire protection. In short, it means that, for example, a CO ₂ extinguisher is connected to the inlet 11 so that the flow of gas is inert and not combustible. This is to avoid the increased risk if a fire should occur. Other components and conditions as before.

Figure 4 shows the same safety hose 10 as in Figure 1, but with a device functioning as an anti-collapse protection. This means that it is important that the safety hose 10 will not be able to collapse or fold flat. As shown is a coil 50 of suitable material mounted in a twisted way around the main hose 1. Thus, helix 50 occupies the cavity 5 between the main hose 1 and second hose 2, but not narrower than the air/inert gas passes in the cavity 5. Figure 5 shows a composite safety hose 10 where the respective variants from Figure 1 to 4 is incorporated in one and the same hose. This will not be reviewed again.

Figure 6 shows a more complete system for automatic monitoring of a safety hose 10 according to the invention. The system includes a control unit 80, a transmitter unit 81 and a forwarding unit 82 As additional parts of the system includes a controlled switching valve 70, a controlled switching and regulating valve 71, a pressure tester 72, a nitrogen tank 73 for pressure testing and a sensor 74 that will detect pressure drop during pressure tests.