any advice on 1/6hp sump pump/ice eaters

jimbob1603 · 02-03-2005, 10:02 AM

Hi ITD,

I started off with a system from dockbubbler.com. The linear compressor is excellent (I have their #DB150L), but I did not like the perforated poly-hose they supplied; the slits were too small; preventing proper air flow. I chucked theirs and made my own from PVC pipe (it is cheaper and performs better).

My linear compressor emits a slight hum which is inaudible @ 20 ft. An underwater circulator probably makes no noticable noise (unless you're a fish).

The whole 'dock de-icing thing' relies on two premises: moving water can't freeze; and, the lake water below the ice is warmer than the ice up above (lake ice is typically formed from the top down). Keeping these two postulates in mind: while you don't want to create waves, you do want to keep the water circulating. If you can't see any small surface currents resulting from your circulator or bubbler, its not properly installed.

I would not put too much faith in 'rated' power consumptiom. The stated numbers usually include the starting load and are high; probably to cover the manufacturer's butts from a legal point of view. Its been my experience that if a tag says a motor consumes X amps or watts, you can expect reality to be about 1/2 of X.

Its also wise to understand the differences of the many different types of air compressors available to the American consumer: screw, reciprocating, linear, oiless, regenerative blower etc.; and their respective pros & cons. I believe that only a linear compressor is practically suited for dock de-icing purposes because it has low power consumption, its quiet, and it is designed for 24 x 7 x 52 use.

There is one significant caution with dock bubblers. If you have an extended power outage, water may enter the air line and freeze; preventing any future 'bubble action' until spring thaw. However, prudent installation and a pneumatic check valve will virtually eliminate this risk.

I'll be going up to the lake in a few weeks, just to check things out. I'll bring an amp-probe and get the low down on power consumption of my linear compressor. I beleive that it was listed at 125 watts, but I can't be sure.

With a little research, I found out that www.dockbubbler.com is actually a retail front-end for a manufacturing company called LMI (http://www.lmimg.com/silent_air_pumps.asp). And LMI is an OEM supplier of linear compressors for Gast. I trust anything Gast sells.

j

ApS · 02-04-2005, 11:25 AM

I gather that a linear compressor is the same thing as what we used to call an oilless compressor? (As opposed to a reciprocating compressor).

I've seen a pair of concrete-filled steel pilings pushed sideways (to shore), but never towards shore.

Anyone seen the benefits of steel pilings instead of wood pilings in your neighborhood? (With or without "Ice-Eaters").

jimbob1603 · 02-04-2005, 12:51 PM

Hi,
All linear compressors are oil-less. But, I do not believe that all oil-less compressors are linear:

Linear compressor:
low power consumption
low pressure (1 - 10 psi) / high volume output
quiet operation
designed for continuous operation
linear magnet drive
purchased at specialty shops & commercial suppliers

Oil-less compressor:
high power consumption
high pressure (50 - 150 psi) / low volume output
very noisy operation
designed for intermittent operation
motor driven diaphragm
purchased at Home Depot

I don't think the ice has any particular direction it will push/drag the pilings. Its probably mostly influenced by water current and wind direction. The 'thermal expansive properties' of water/ice are tremendous; nothing will stop the ice from compressing/damaging (however minimal) any piling. The thicker the ice, the more potential for damage.

Wood is the cheapest material; then steel; and aluminum being the most expensive. Concrete pilings, without some sort of steel reinforcing, is a bad choice. Concrete has superb compressive strength, but poor tensile and shear strength.

I would never use steel in a marine environment, for obvious reasons; and probably not even in fresh water .... just too much maintenance. I'd use a 6063 alloy aluminum in fresh water (if cost was not an issue ..... a 4x4x3/16 Al tube is 4 times the price of a 4x6 PT timber). All said and done, wood is the preferred material; and wood is probably the most forgiving when it comes to ice damage.
j

02-03-2005, 10:02 AM	#1
jimbob1603 Senior Member Join Date: May 2004 Posts: 71 Thanks: 0 Thanked 0 Times in 0 Posts	Cost of Electricity .... the nuts & bolts of the question Hi ITD, I started off with a system from dockbubbler.com. The linear compressor is excellent (I have their #DB150L), but I did not like the perforated poly-hose they supplied; the slits were too small; preventing proper air flow. I chucked theirs and made my own from PVC pipe (it is cheaper and performs better). My linear compressor emits a slight hum which is inaudible @ 20 ft. An underwater circulator probably makes no noticable noise (unless you're a fish). The whole 'dock de-icing thing' relies on two premises: moving water can't freeze; and, the lake water below the ice is warmer than the ice up above (lake ice is typically formed from the top down). Keeping these two postulates in mind: while you don't want to create waves, you do want to keep the water circulating. If you can't see any small surface currents resulting from your circulator or bubbler, its not properly installed. I would not put too much faith in 'rated' power consumptiom. The stated numbers usually include the starting load and are high; probably to cover the manufacturer's butts from a legal point of view. Its been my experience that if a tag says a motor consumes X amps or watts, you can expect reality to be about 1/2 of X. Its also wise to understand the differences of the many different types of air compressors available to the American consumer: screw, reciprocating, linear, oiless, regenerative blower etc.; and their respective pros & cons. I believe that only a linear compressor is practically suited for dock de-icing purposes because it has low power consumption, its quiet, and it is designed for 24 x 7 x 52 use. There is one significant caution with dock bubblers. If you have an extended power outage, water may enter the air line and freeze; preventing any future 'bubble action' until spring thaw. However, prudent installation and a pneumatic check valve will virtually eliminate this risk. I'll be going up to the lake in a few weeks, just to check things out. I'll bring an amp-probe and get the low down on power consumption of my linear compressor. I beleive that it was listed at 125 watts, but I can't be sure. With a little research, I found out that www.dockbubbler.com is actually a retail front-end for a manufacturing company called LMI (http://www.lmimg.com/silent_air_pumps.asp). And LMI is an OEM supplier of linear compressors for Gast. I trust anything Gast sells. j Last edited by jimbob1603; 02-04-2005 at 10:19 AM.

02-04-2005, 11:25 AM	#2
ApS Senior Member Join Date: Jan 2005 Location: Florida (Sebring & Keys), Wolfeboro Posts: 5,943 Thanks: 2,218 Thanked 779 Times in 555 Posts	Oilless? I gather that a linear compressor is the same thing as what we used to call an oilless compressor? (As opposed to a reciprocating compressor). I've seen a pair of concrete-filled steel pilings pushed sideways (to shore), but never towards shore. Anyone seen the benefits of steel pilings instead of wood pilings in your neighborhood? (With or without "Ice-Eaters"). __________________ Is it "Common Sense" isn't.

02-04-2005, 12:51 PM	#3
jimbob1603 Senior Member Join Date: May 2004 Posts: 71 Thanks: 0 Thanked 0 Times in 0 Posts	More Hi, All linear compressors are oil-less. But, I do not believe that all oil-less compressors are linear: Linear compressor: low power consumption low pressure (1 - 10 psi) / high volume output quiet operation designed for continuous operation linear magnet drive purchased at specialty shops & commercial suppliers Oil-less compressor: high power consumption high pressure (50 - 150 psi) / low volume output very noisy operation designed for intermittent operation motor driven diaphragm purchased at Home Depot I don't think the ice has any particular direction it will push/drag the pilings. Its probably mostly influenced by water current and wind direction. The 'thermal expansive properties' of water/ice are tremendous; nothing will stop the ice from compressing/damaging (however minimal) any piling. The thicker the ice, the more potential for damage. Wood is the cheapest material; then steel; and aluminum being the most expensive. Concrete pilings, without some sort of steel reinforcing, is a bad choice. Concrete has superb compressive strength, but poor tensile and shear strength. I would never use steel in a marine environment, for obvious reasons; and probably not even in fresh water .... just too much maintenance. I'd use a 6063 alloy aluminum in fresh water (if cost was not an issue ..... a 4x4x3/16 Al tube is 4 times the price of a 4x6 PT timber). All said and done, wood is the preferred material; and wood is probably the most forgiving when it comes to ice damage. j Last edited by jimbob1603; 02-04-2005 at 04:18 PM.