Safety measures to take on equipment..

Steven Button

Administrator
Seen a couple of threads recently discussing actual accidents that have happened related to equipment failure and the possibility of accidents happening from 'poorly' designed equipment.

Thought it would be good to hear what safety measures/devices should be used to safeguard our equipment and people using our equipment.

Where should a pressure relief valve or burst disc be located - what does it do and why do we need it.

How do we install a low water shut off in our water tanks, where can we get one?

Pressure switches? what are they? what do they do? where are they/should they be located?

anything else we should consider?
 
Where should a pressure relief valve or burst disc be located - what does it do and why do we need it. The pressure relief valve should be on the inlet of the coil, the burst disc goes on the outlet.

How do we install a low water shut off in our water tanks, where can we get one? A small float switch mounted low in the tank would do that. It could be set up to ground the ignition system, shutting down the engine, or through a relay to at least cut the burner off.

Pressure switches? what are they? what do they do? where are they/should they be located?Pressure switches are spring loaded. The operating pressure overrides the spring tension and activates a microswitch. The best place to mount one is on the head of the pump, or the port on the unloader which sees head pressure. As Nigel pointed out, they can be wired in with a flow switch for a "checks and balances" kind of operation, ie., sensing both pressure and flow to activate the burner.

anything else we should consider?

A thermostat or high limit switch on the outlet is another preferred safety, although this switch would never see the temps to shut down in the recent steam blowout scenario. The water in a small area of the coil superheated quickly, and the heat would not have time to convect through the water in the coil to shut the burner off.

The best safety devices? A vigilant eye and ear. If something doesn't look or sound right...investigate.
 
Is the burst disk and pressure relief valve an either/or safety or do you want both - what does one cover that the other doesn't?

I put a relief valve on the pump head and one at the coil inlet - seemed like a good idea.

I did have the burner stay on once and the relief valve popped and saved the day!

If they do 'pop' should they be replaced?
 
Seen a couple of threads recently discussing actual accidents that have happened related to equipment failure and the possibility of accidents happening from 'poorly' designed equipment.

Thought it would be good to hear what safety measures/devices should be used to safeguard our equipment and people using our equipment.

Where should a pressure relief valve or burst disc be located - what does it do and why do we need it.

How do we install a low water shut off in our water tanks, where can we get one?

Pressure switches? what are they? what do they do? where are they/should they be located?

anything else we should consider?

Steven... This is the one I use.... http://www.gemssensors.com/content.aspx?id=376

You have to ask for the DRY SINK. Part #187580 for the 10-28 volt

The dry sink senses when there is no water on sensor.

It is $105 plus shipping

I have a pic or video somewhere. Trying to do too many thing at once right now. I'll have some edited footage before winter is over. LOL
 
Steven... This is the one I use.... http://www.gemssensors.com/content.aspx?id=376

You have to ask for the DRY SINK. Part #187580 for the 10-28 volt

The dry sink senses when there is no water on sensor.

It is $105 plus shipping

I have a pic or video somewhere. Trying to do too many thing at once right now. I'll have some edited footage before winter is over. LOL

Forgot to say that you want it mounted directly right above your outlet bulkhead fitting just in case the trailer/tank is on unlevel ground you will be sensing the water level where it counts.
 
I'm going to retract some of what I said earlier. With a flow switch, the relief valve should be mounted on the pump or on the pump side of the flow switch. If the valve blows, flow through the switch will cease, shutting off the burner. With a pressure switch, it doesn't matter, as the relief valve maintains some system pressure, so the pressure switch will remain activated.


Tom, a relief valve is a necessity, a burst disc is optional. Hydro Tek uses both, most manufacturers only use the relief valve. Hydro Tek also builds many of their skids with a pressure switch on the unloader and a flow switch at the coil inlet.
 
A thermostat or high limit switch on the outlet is another preferred safety, although this switch would never see the temps to shut down in the recent steam blowout scenario. The water in a small area of the coil superheated quickly, and the heat would not have time to convect through the water in the coil to shut the burner off.

The best safety devices? A vigilant eye and ear. If something doesn't look or sound right...investigate.

Thanks for the explanations Russ, you've got a great way of explaining things... you make it sound easy!!! LOL :thumbup2:
 
I'm going to retract some of what I said earlier. With a flow switch, the relief valve should be mounted on the pump or on the pump side of the flow switch. If the valve blows, flow through the switch will cease, shutting off the burner. With a pressure switch, it doesn't matter, as the relief valve maintains some system pressure, so the pressure switch will remain activated.



Tom, a relief valve is a necessity, a burst disc is optional. Hydro Tek uses both, most manufacturers only use the relief valve. Hydro Tek also builds many of their skids with a pressure switch on the unloader and a flow switch at the coil inlet.


Great Info Russ J. Could you post an electrical drawing of the switches/controls in a system?

How often do you think the control/safety devices should be changed, in hours?
 
Steven, I have used this switch with good results. You'll have to install a 1/2" bukhead connector in the tank to mount it.

http://www.liquidlevel.com/products_switches_standard_hz_SM-1000-PP.asp

Thanks

I'm going to retract some of what I said earlier. With a flow switch, the relief valve should be mounted on the pump or on the pump side of the flow switch. If the valve blows, flow through the switch will cease, shutting off the burner. With a pressure switch, it doesn't matter, as the relief valve maintains some system pressure, so the pressure switch will remain activated.


Tom, a relief valve is a necessity, a burst disc is optional. Hydro Tek uses both, most manufacturers only use the relief valve. Hydro Tek also builds many of their skids with a pressure switch on the unloader and a flow switch at the coil inlet.

To be honest I've only really paid attention to these parts on my Hydrotek skid in the last few months, both of the relief valves have done their job! I just followed instructions I found online for 'resetting' them and they both appeared to be back to normal.... to echo Tom's question, should they be replaced?
 
Forgot to say that you want it mounted directly right above your outlet bulkhead fitting just in case the trailer/tank is on unlevel ground you will be sensing the water level where it counts.

Thanks Mike, that's good info... when I moved the equipment over to the flatbed I noticed exactly the problem you are highlighting. I left the low water cut-off on the side of the tank after moving supply bulkhead to middle of tank - parking on cambered roads I noticed an uneven water level.
 
Great Info Russ J. Could you post an electrical drawing of the switches/controls in a system?

wiring.jpg

I know this diagram is pretty faint. That's about the best I could scan it. I think they draw it light on purpose.lol


How often do you think the control/safety devices should be changed, in hours?

When they go bad. There's no set life cycle for them.
 
This is great. Now I know what all that stuff is on my skid. I blew out a burst disc last year. I took it into the shop and they did some tests on it and I haven't had a problem since. It's good to know how this works though, so I can understand it and fix it on the spot if I need to.
 
Know you controls !!

Wow, I'm going to spend some time on this thread a little later,
but this stuff is severely important.. So I'm going to spend a minute..
That float-switch inthe water tank is golden.. we install 'em all the time..
One wire goes to ground, the other goes to the engine ignition-kill, or..
use it to shut off the fuel solenoid on the heater, so you have a "hint"
..instead of a rude interruption, when the water level is just low.
we have 'em for $39.50 including a free schematic.

Flow switches to control heat should be required by law.
and the redundant pressure switch we recommend all the time.
Temperature controls should be rated as "tight" as possible..
we use a 200degr.F hi-limit on the heater, if the system is adjusted for 190 max.
we also use a 140 degrewe high-limit on the heater inlet, so when the flow switch fails, and the heat is on with NO water flowing,
the 140degr. limit saves the heater coil LONG before the heat would get to the heater outlet where the 200degr. limit is..
We have only lost 3 heater coils at less than 12 years old in the last 25 years.. that is huge reliability! most coils only last 7 or 8 years.
We don't use adjustable temp controls unless the application requires it, or the owner demands it..
they are not hemetically sealed, and the machine will typically "eat one" about as often as you'll kill a pressure switch.. every 12 months.

Be really careful around Pressure relief valves..
Make sure you get one with a stainless steel ball, NOT rubber !..
When water passes the rubber one the first time, a groove is cut..
you then have to "mash down" on the valve ball to get it to seal again, which sets the relief point rediculously high..
it won't work when you need it.
I use the Adams regulating relief valve (about $37.50) or the Giant brand pop-off ($19.90)

OK, this took more than a minute, but few people in this industry understand this stuff, and I figure y'all are a good investment of my time. Eh?

Jerry McMillen
call 800-400-2532<O:p</O:p
jerry@PressureWasher.net www.PressureWasher.net<O:p</O:p
mfr. of BullDogPro Industrial Water Blasters,
VacuBerm Reclaim tools, and Sirocco Performance Vacuums.
 
Wow, I'm going to spend some time on this thread a little later,
but this stuff is severely important.. So I'm going to spend a minute..
That float-switch inthe water tank is golden.. we install 'em all the time..
One wire goes to ground, the other goes to the engine ignition-kill, or..
use it to shut off the fuel solenoid on the heater, so you have a "hint"
..instead of a rude interruption, when the water level is just low.
we have 'em for $39.50 including a free schematic.

Flow switches to control heat should be required by law.
and the redundant pressure switch we recommend all the time.
Temperature controls should be rated as "tight" as possible..
we use a 200degr.F hi-limit on the heater, if the system is adjusted for 190 max.
we also use a 140 degrewe high-limit on the heater inlet, so when the flow switch fails, and the heat is on with NO water flowing,
the 140degr. limit saves the heater coil LONG before the heat would get to the heater outlet where the 200degr. limit is..
We have only lost 3 heater coils at less than 12 years old in the last 25 years.. that is huge reliability! most coils only last 7 or 8 years.
We don't use adjustable temp controls unless the application requires it, or the owner demands it..
they are not hemetically sealed, and the machine will typically "eat one" about as often as you'll kill a pressure switch.. every 12 months.

Be really careful around Pressure relief valves..
Make sure you get one with a stainless steel ball, NOT rubber !..
When water passes the rubber one the first time, a groove is cut..
you then have to "mash down" on the valve ball to get it to seal again, which sets the relief point rediculously high..
it won't work when you need it.
I use the Adams regulating relief valve (about $37.50) or the Giant brand pop-off ($19.90)

OK, this took more than a minute, but few people in this industry understand this stuff, and I figure y'all are a good investment of my time. Eh?

Jerry McMillen
call 800-400-2532<O:p</O:p
jerry@PressureWasher.net www.PressureWasher.net<O:p</O:p
mfr. of BullDogPro Industrial Water Blasters,
VacuBerm Reclaim tools, and Sirocco Performance Vacuums.

When you told me than no one does safety like you guys, I see what you mean.
 
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