stuffing box question

[mmd]

I have just fielded a question that has me stumped (I know, I know... us boat designer types are s'posed to know everything boaty, right?) What is the normal operating temperature of a packing-type stuffing box? A client wants to install a temperature sensor as part of an unmanned engine room monitoring system and we need to know where to set the alarm point.

I don't mean to offend any well-meaning Forumite who wants to help with my next statement, but... I need hard, defensible data; i.e., "Brand X suggests a max operating temp of XX degrees", not (as interesting and often useful as these statemets are) "Old Charlie down at Joe's Marina and Used Rope Emporium says that if you can lay your hand on the stuffing box for the length of time it takes to put a chaw of tobaccy in your mouth..."

Thanks in advance to any & all who can offer help.

[FAST FRED]

The old flax (or teflon coated Flax) does run warm , hot 125 or so to the touch.And it MUST drip for cooling purposes.

The fancy ceramic sealed is a pain, IF a bladder leaks or is not replaced often enough , down you go.Big pain to install the bladder!
It also needs a pressurized water supply , more to install, maintain,break, UGH.

I have had great luck with the Gore packing , does not need to drip , it runs cool , and maintains the adjustment for hundreds of hours.While tight , no drip the laiser read 90F.

Instead of a temp gage , a grease hose to the stuffing box , and turn cup of grease can allow the flax stuffing to be water tight when the boat is out of service. A turn of the cup will force enough grease in place to stop the annoying dripping.

Boat user , and builder, amateur designer.

FF

[tom kane]

Most stuffing boxes are fitted too low... on the keelson (A bad tradition) If fitted as close as possible to the thrust brg extra height (possibly above water level) may even give a complete drip free seal which can be water cooled and lubed.If it is possible to fit above static boat waterline you will not have to worry about a leak.The pressure difference between high and low fitting gives advantages anyway.

[TerryKing]

[quote=mmd;166673..(snip).. client wants to install a temperature sensor as part of an unmanned engine room monitoring system and we need to know where to set the alarm point.[/QUOTE]

mmd, I don't have data for you; if you want a generalized answer, the manufacturer needs to supply it.

I would much prefer a system where all ER data is characterized under a 'nominal' run or set of runs at different speeds, and then an absolute value alarm setpoint is defined, AND a "rate of change of value" setpoint is also defined.

If a stuffing box's 'normal' temperature is 100F, and the boat gets underway and in 30 seconds the temperature is 90F something's happening, and it's not good!