Safety mechanism for use with a drum unloader

1. An apparatus for forcing a viscous material to flow from a storage container, the apparatus comprising:

a follower plate configured to be inserted into an open-end of the storage container; the follower plate being located in a position that is either outside or inside the storage container;

a sealing element located around the outer periphery of the follower plate, the sealing element configured to provide a leak-proof seal with the storage container when the follower plate is located inside the storage container;

a pump assembly that includes a pump, an air motor, and a pipe or tube that is in fluid communication with the follower plate; the air motor being supplied with a source of air pressure;

a support stand comprising a base, a crossbar; and two or more cylinders with rods inserted therein; the cylinders and rods configured to move the follower plate up or down based on air pressure supplied thereto;

one or more control systems; and

a safety mechanism configured to reversibly allow or prevent the air pressure from being supplied to the air motor depending upon the position of the follower plate;

wherein the safety mechanism comprises:

a first valve configured to reversibly switch between on and off in order to allow or prevent air pressure from flowing from the source to the air motor;

at least one device configured to measure the position of the follower plate relative to the storage container; and

a second valve that is in communication with the first valve and the device; the second valve configured to instruct the first valve to prevent air pressure from being supplied to the air motor when the follower plate is outside of the storage container.

2. The apparatus according to claim 1 , wherein the second valve is further configured to instruct the first valve to allow air pressure from the source to be supplied to the air motor when the follower plate is inside of the storage container.

3. The apparatus according to claim 1 , wherein the second valve is an air-operated or electric pilot valve.

4. The apparatus according to claim 1 , wherein the first valve is a solenoid valve.

5. The apparatus according to claim 1 , wherein the air motor increases the air pressure received from the source by at least 10-fold in order to cause the viscous material to flow from the storage container.

6. The apparatus according to claim 1 , wherein the viscous material has a viscosity of 30,000 millipascal-seconds (centipoise) or greater.

7. The apparatus according to claim 1 , wherein the storage container is a 55-gallon drum, a 5-gallon pail, or a 1-gallon can.

8. The apparatus according to claim 1 , wherein the follower plate is configured to include one or more thermal elements capable of heating the material in the storage container.

9. A safety mechanism for use in an apparatus that includes an air motor-driven pump assembly, a follower plate, a sealing element, a stand, and at least one controller, wherein the apparatus forces a viscous material to flow from a storage container, the safety mechanism comprising:

a first valve configured to reversibly switch between on and off in order to allow or prevent air pressure from flowing from a source to the air motor-driven pump assembly;

at least one device configured to measure the position of the follower plate relative to the storage container; and

a second valve that is in communication with the first valve and the device; the second valve configured to instruct the first valve to prevent air pressure from being supplied to the air motor-driven pump assembly when the follower plate is external to the storage container.

10. The safety mechanism according to claim 9 , wherein the second valve is further configured to instruct the first valve to allow air pressure from the source to be supplied to the air motor-driven pump assembly when the follower plate is within the storage container.

11. The safety mechanism according to claim 9 , wherein the second valve is an air-operated or electric pilot valve.

12. The safety mechanism according to claim 9 , wherein the first valve is a solenoid valve.

13. A method of removing a viscous material from a storage container, the method comprising the steps of:

a) providing a source of air pressure;

b) providing an apparatus configured to force the viscous material to flow from the storage container; the apparatus comprising an air motor-driven pump assembly, a follower plate, a sealing element, a stand, at least one controller, and a safety mechanism, wherein the safety mechanism reversibly allows or prevents air pressure from being supplied from the source to the air motor-driven pump assembly depending upon the position of the follower plate, the safety mechanism comprising:

a first valve configured to reversibly switch between on and off in order to allow or prevent air pressure from flowing from the source to the air motor;

at least one device configured to measure the position of the follower plate relative to the storage container; and

a second valve that is in communication with the first valve and the device; the second valve configured to instruct the first valve to prevent air pressure from being supplied to the air motor when the follower plate is outside of the storage container;

c) providing the storage container of the viscous material;

d) positioning the follower plate inside the open-end of the storage container;

e) allowing air pressure to flow from the source to the air motor-driven pump assembly; and

f) causing a pump to evacuate viscous material from the storage container by flowing through the pump assembly.

14. The method according to claim 13 , wherein the second valve is further configured to instruct the first valve to allow air pressure from the source to be supplied to the air motor when the follower plate is inside of the storage container.

15. The method according to claim 13 , wherein the second valve is an air-operated or electric pilot valve and the first valve is a solenoid valve.

16. The method according to claim 13 , wherein the method further comprises:

g) stopping the downward movement of the follower plate when the follower plate approaches the bottom of the storage container; the storage container now becoming an empty container;

h) moving the follower plate in an upward direction until it reaches a position that is above the open-end of the empty container;

i) allowing the safety mechanism to prevent air pressure from being supplied from the source to the air motor-driven pump assembly;

j) removing the empty container;

k) providing another storage container of the viscous material; and

l) repeating steps d), e), and f).

17. The use of the apparatus that includes the safety mechanism according to claim 9 .