DREDGING TIPS
Nov 11, 2008 13:51:28 GMT 12
Post by RKC on Nov 11, 2008 13:51:28 GMT 12
DREDGING TIPS
DREDGE ENGINE AIR FILTERS.
Dredge engines operate in a relatively dust free environment and therefore don't necessarily require the typical standard air filter that is supplied with stationary engines. Stock standard air filters can be replaced with an after market filter that is designed to permit free air flow. Or alternatively, the standard filter can be modified.
Freeing up air flow has the advantage of producing a little more, but noticeable, power from the engine.
When I was dredging in Victoria (Australia) I used 10 hp Honda engines and modified the standard filters to free up air flow. I started by taking the filter off the engine and removing the plastic cover along with the foam. I then put the filter in the camp fire to burn the paper filter. Then once the filter had cooled I would clean off the ash and put the foam back on the filter. I found that the foam filter alone was more than sufficient to protect the engine in the relatively dust free environment of a river system. As a precaution I had to check the foam regularly when it would be cleaned in soapy water, dried and then re oiled.
SYNTHETIC OIL IN DREDGE ENGINES.
Professional dredgers often prefer to use a fully synthetic oil, such as Mobil 1, in their dredge engines as synthetic oil will reduce friction in an engine cylinder. Dredge engines can then be run at a reduced revs, which will lengthen engine life.
A new engine will contain a petroleum based oil of the manufactures recommended viscosity and will need to be replaced. However, before replacing the petroleum based oil with a synthetic oil, its important to first run-in the engine. The run-in period can be for up to 10 hours and during the run-in period its preferable 'not' to have a load on the motor and to run the motor at minimum revs.
CARBON BUILD UP IN ENGINES.
Its worthwhile occasionally removing an engines upper cylinder body to examine for carbon build up which can effect the efficiency of stationary engines.
HOW TO GET INTO A WET SUIT.
Plastic bags can be used to make getting into a wet suit considerably easier. Scuba divers have used plastic bags for many years as have many professional dredges, and using plastic bags significantly assists putting on a wet suit. Any plastic bags can be used and are first placed over the feet. The wet suit will then slide on with little effort. The bags are then removed before adding any footwear.
WATER CONTAMINATION OF FUEL.
Professional dredgers need to be constantly alert for the contamination of petrol with water. Fuel contamination can shut down a dredging operation, often at the worst possible time, and significant additional time can be lost getting engines restarted after water gets into the engine.
Being alert to water contamination means simply examining fuel before its poured into the engine fuel tank.
When storing 44 gal drums of fuel keep them covered from the rain so water will not collect around the rim of the drum and seep into the drum. And try to keep fuel drums as full as possible to avoid condensation.
There are additives that can be added to fuel to treat water contamination, but they are of limited use ... and if too much is added, the engine will stop and need a thorougher clean before restarting.
On the larger engines, fuel filters or bowls are a worthwhile preventive measure. But they do need to be regularly checked.
BUSH ANIMALS
Never leave any dredge equipment such as demand valves and dive masks laying on the river bank overnight as they are likely to be damaged by bush animals.
In North Queensland, white-tailed rats will chew holes in rubber and quickly destroy equipment such as demand valves. And in New Zealand possums can be equally destructive. In the high country of Otago, Keas will pick up in their beak anything of a bright color and fly away with it.
DREDGE SPARES.
On any production dredge its advisable to always have some spare parts and tools close at hand. And when dredging remote areas its 'essential' to have plenty of spares with the dredge at all times.
Typical dredge spares would include, pump seals, spark plugs, air compressor parts, hose clamps and so on. Diving gear such as snorkels and face masks can easily be dropped into the water where the current will wash them away. Spares of any equipment that is small and floats should always be on hand.
STORING DREDGE ENGINES
Professional dredgers are often required to store their engines for considerable periods of time, and precautions need to be taken to prevent corrosion of the engine during the storage period.
To prepare an engine for storage, first the petrol needs to be drained from the fuel tank. Then the spark plug should be removed and engine oil poured into the cylinder until it fills. The spark plug can then be screwed back in to seal the cylinder.
Then, to protect the outside of the engine, fish oil should be liberally sprayed on all exposed parts of the engine.
If the engine is being stored outdoors, it, obviously, needs to be protected from the elements by covering. However the engine should never be wrapped in plastic as this will result in corrosive condensation ... especially in a humid environment. Air must be able to freely circulate around the engine body.
During the 1980s the Queensland dredgers who worked in the remote rivers of the coastal tropical rain-forest would take their engines off their dredges and store them above the high water mark during the Wet Season which would last about 2-3 months. These engines were subject to the most corrosive environment imaginable, of extremely high humidity combined with frequent heavy tropical downpours. However, by taking the above simple preventive measures, the engines did not corrode and would often start on the first attempt.
KICK STARTING ENGINES
Dredge engines that are difficult to start can often be "kick started" by taking out the spark plug and then pouring a small quantity of petrol in the cylinder. The spark plug then needs to be quickly put back and the engine started.
This can be a handy way to get a troublesome engine started when in a remote area away from any repair facilities and to get the engine restarted so the dredging day can be completed without downtime during the precious daylight hours.
SPILL TRAY
Its preferable to have a spill tray added on any dredge (under the engine) intended for use in Otago Province.
The regulations (Water Plan) relating to suction dredging applicable to Otago, state :"Suction dredge mining within the bed of a river is a permitted activity providing: No refueling is carried out while the dredge is within the wet bed of the river unless an effective spill tray has been installed."
Full ORC suction dredging permitted activity regulations, see Otago Regional Council "Water Plan".
CLEANING DEMAND VALVES
The method most commonly employed by professional dredgers to clean demand valves is by soaking the valve in a dilute solution of vinegar (apx 50% vinegar and 50% water). For a more thorougher cleaning, the valve can be first soaked in soapy water, then rinsed and then soaked in a solution of dilute vinegar.
img.photobucket.com/albums/v521/NZGOLD/Equipment/cromAAAA_14.jpg
Its important never to attempt to clean a demand valve by immersing it in hot water. Hot water will damage a demand valve beyond repair as some of the plastic parts of the valve can easily melt.
TOOLS
Any tools used underwater, such as pry bars and hammers, should be painted with a bright color paint. The bright color will allow the tools to be easily noticeable so they can be picked up quickly when needed without having to look around to find them, and they are then less likely to be covered (and lost) by the tailings from the dredge.
DREDGE ENGINE AIR FILTERS.
Dredge engines operate in a relatively dust free environment and therefore don't necessarily require the typical standard air filter that is supplied with stationary engines. Stock standard air filters can be replaced with an after market filter that is designed to permit free air flow. Or alternatively, the standard filter can be modified.
Freeing up air flow has the advantage of producing a little more, but noticeable, power from the engine.
When I was dredging in Victoria (Australia) I used 10 hp Honda engines and modified the standard filters to free up air flow. I started by taking the filter off the engine and removing the plastic cover along with the foam. I then put the filter in the camp fire to burn the paper filter. Then once the filter had cooled I would clean off the ash and put the foam back on the filter. I found that the foam filter alone was more than sufficient to protect the engine in the relatively dust free environment of a river system. As a precaution I had to check the foam regularly when it would be cleaned in soapy water, dried and then re oiled.
SYNTHETIC OIL IN DREDGE ENGINES.
Professional dredgers often prefer to use a fully synthetic oil, such as Mobil 1, in their dredge engines as synthetic oil will reduce friction in an engine cylinder. Dredge engines can then be run at a reduced revs, which will lengthen engine life.
A new engine will contain a petroleum based oil of the manufactures recommended viscosity and will need to be replaced. However, before replacing the petroleum based oil with a synthetic oil, its important to first run-in the engine. The run-in period can be for up to 10 hours and during the run-in period its preferable 'not' to have a load on the motor and to run the motor at minimum revs.
CARBON BUILD UP IN ENGINES.
Its worthwhile occasionally removing an engines upper cylinder body to examine for carbon build up which can effect the efficiency of stationary engines.
HOW TO GET INTO A WET SUIT.
Plastic bags can be used to make getting into a wet suit considerably easier. Scuba divers have used plastic bags for many years as have many professional dredges, and using plastic bags significantly assists putting on a wet suit. Any plastic bags can be used and are first placed over the feet. The wet suit will then slide on with little effort. The bags are then removed before adding any footwear.
WATER CONTAMINATION OF FUEL.
Professional dredgers need to be constantly alert for the contamination of petrol with water. Fuel contamination can shut down a dredging operation, often at the worst possible time, and significant additional time can be lost getting engines restarted after water gets into the engine.
Being alert to water contamination means simply examining fuel before its poured into the engine fuel tank.
When storing 44 gal drums of fuel keep them covered from the rain so water will not collect around the rim of the drum and seep into the drum. And try to keep fuel drums as full as possible to avoid condensation.
There are additives that can be added to fuel to treat water contamination, but they are of limited use ... and if too much is added, the engine will stop and need a thorougher clean before restarting.
On the larger engines, fuel filters or bowls are a worthwhile preventive measure. But they do need to be regularly checked.
BUSH ANIMALS
Never leave any dredge equipment such as demand valves and dive masks laying on the river bank overnight as they are likely to be damaged by bush animals.
In North Queensland, white-tailed rats will chew holes in rubber and quickly destroy equipment such as demand valves. And in New Zealand possums can be equally destructive. In the high country of Otago, Keas will pick up in their beak anything of a bright color and fly away with it.
DREDGE SPARES.
On any production dredge its advisable to always have some spare parts and tools close at hand. And when dredging remote areas its 'essential' to have plenty of spares with the dredge at all times.
Typical dredge spares would include, pump seals, spark plugs, air compressor parts, hose clamps and so on. Diving gear such as snorkels and face masks can easily be dropped into the water where the current will wash them away. Spares of any equipment that is small and floats should always be on hand.
STORING DREDGE ENGINES
Professional dredgers are often required to store their engines for considerable periods of time, and precautions need to be taken to prevent corrosion of the engine during the storage period.
To prepare an engine for storage, first the petrol needs to be drained from the fuel tank. Then the spark plug should be removed and engine oil poured into the cylinder until it fills. The spark plug can then be screwed back in to seal the cylinder.
Then, to protect the outside of the engine, fish oil should be liberally sprayed on all exposed parts of the engine.
If the engine is being stored outdoors, it, obviously, needs to be protected from the elements by covering. However the engine should never be wrapped in plastic as this will result in corrosive condensation ... especially in a humid environment. Air must be able to freely circulate around the engine body.
During the 1980s the Queensland dredgers who worked in the remote rivers of the coastal tropical rain-forest would take their engines off their dredges and store them above the high water mark during the Wet Season which would last about 2-3 months. These engines were subject to the most corrosive environment imaginable, of extremely high humidity combined with frequent heavy tropical downpours. However, by taking the above simple preventive measures, the engines did not corrode and would often start on the first attempt.
KICK STARTING ENGINES
Dredge engines that are difficult to start can often be "kick started" by taking out the spark plug and then pouring a small quantity of petrol in the cylinder. The spark plug then needs to be quickly put back and the engine started.
This can be a handy way to get a troublesome engine started when in a remote area away from any repair facilities and to get the engine restarted so the dredging day can be completed without downtime during the precious daylight hours.
SPILL TRAY
Its preferable to have a spill tray added on any dredge (under the engine) intended for use in Otago Province.
The regulations (Water Plan) relating to suction dredging applicable to Otago, state :"Suction dredge mining within the bed of a river is a permitted activity providing: No refueling is carried out while the dredge is within the wet bed of the river unless an effective spill tray has been installed."
Full ORC suction dredging permitted activity regulations, see Otago Regional Council "Water Plan".
CLEANING DEMAND VALVES
The method most commonly employed by professional dredgers to clean demand valves is by soaking the valve in a dilute solution of vinegar (apx 50% vinegar and 50% water). For a more thorougher cleaning, the valve can be first soaked in soapy water, then rinsed and then soaked in a solution of dilute vinegar.
img.photobucket.com/albums/v521/NZGOLD/Equipment/cromAAAA_14.jpg
Its important never to attempt to clean a demand valve by immersing it in hot water. Hot water will damage a demand valve beyond repair as some of the plastic parts of the valve can easily melt.
TOOLS
Any tools used underwater, such as pry bars and hammers, should be painted with a bright color paint. The bright color will allow the tools to be easily noticeable so they can be picked up quickly when needed without having to look around to find them, and they are then less likely to be covered (and lost) by the tailings from the dredge.