Best place to measure temp? And what thermometer to get?

[stormchaser]

I want to get an IR thermometer. Any suggestions? I'd rather NOT spend a fortune, but also don't want junk. Also, when measuring engine temps...trying to compare to the water temp gauge...where should I take the readings? Engines are 8v71TIs...

 

[Passages]

I got one on eBay for around $25. Picked up a phototach for about the same price too.

They were obviously from China but not junk and work fine.

 

[stormchaser]

The photo-tach...what are they and how do you use one? lol

 

[Avenger]

how do you sue one? lol

First, you need a good attorney, of which there is no such thing.

A photo-tach is an optical tachometer. You paste a reflective strip on some rotating component, in this case the damper or flywheel, and aim the unit at it to measure RPM.

Raytech is a good brand of IR temp gun.

 

[stormchaser]

The phototachs...do they come with multiple strips so I can use one for both engines? Are they accurate?

 

[stormchaser]

Also, where should I aim the thermometer to get the best readings?

 

[Pascal]

for coolant, i usually look for the warmest spot, usually near the temp sensor or near the tstat.

when taking measuremnt, try to do it fairly close since the further you are the wider the cone, and keep it consistent.

also, keep in mind that the surface color/material/reflectiveness can affect reading.

 

[Avenger]

The phototachs...do they come with multiple strips so I can use one for both engines? Are they accurate?

They should come with multiple pieces of reflective tape. You should be able to use any reflective tape available in auto part or hardware stores. You may even be able to get away with a clean, sharp stripe of white paint.

These are digital units and should be accurate to +/- 1 RPM or better. Much more accurate than the analog tachs on your instrument panel.

Re: IR temps. Remember you are measuring surface emissivity, not actual coolant temperature. However, you can usually get a reasonably close number by reading the thermostat housing if it's accessible. You should check multiple locations i.e. exhaust manifolds, cylinder heads, turbocharger, transmission housings etc. The important part to to consistenly hit the same spots and compare engine to engine. This way you'll have a baseline to compare to if something gets out of range so you can catch trouble early.

 

[GJH]

I bought my IR Thermometer at Radio Shack, maybe 40 bucks? Works well. In addition to above, I shoot the oil filters, transmissiion and the turbos, the alternators, ambient temp of the ER and the stuffing box. I have some baseline readings that I remembered, so I can note any variance. DD has some of these temp guidelines in their manual.


This is a handy device for a variety of other stuff too, such as various pumps and oneself..

 

[bobk]

An annual IR temperature check of the electrical connections on the panels while under full loads is also a good preventative measure. Poor connections will begin to heat up and can be corrected before a problem starts.

Bob

 

[Boatsb]

I bought my IR Thermometer at Radio Shack, maybe 40 bucks? Works well. In addition to above, I shoot the oil filters, transmissiion and the turbos, the alternators, ambient temp of the ER and the stuffing box. I have some baseline readings that I remembered, so I can note any variance. DD has some of these temp guidelines in their manual.


This is a handy device for a variety of other stuff too, such as various pumps and oneself..

It is also invaluable for the maintenance of beer temp but the cans can be a problem because of refection so get some bottles.

 

[SportFishCruising]

Infrared Thermometers (IR Radiometers) all have a spotsize to distance ratio and minimum spot size resolution. For example, if minimum spot size is 1", the detector recieves all emittance in a one inch circle and computes it average temperature. Now, if the radiometer has a spot size to distance ratio of 5:1, that means at 5 inches away from the object it measures the average temperature of a 1" circle on the surface, at 10 inches away it measures the average of a 2" circle and at 4 feet away it is measuring a 9.6 inch circle; this definitely will effect accuracy and reatability. The higher the ratio, (examples 30:1, 60:1, 90:1) the greater the resolution of the detector, allowing you to measure small objects at greater distances. This is what effects pricing on various models in combination to the detector's temperature measurement range (example -20 to 200 deg. F.)
Realizing the effect on accuracy this spot size to distance ratio has and knowing what your needs are will help select the appropriate model, pricing and effective use of the various models in the market place.
Also, emissivity must be concidered as all objects do not radiate their heat the same. All objects above absolute zero emit heat, that is what IR is measuring, but nothing emits 100% of it's heat. Emissivity is a percentage of that emittance; example 0.90 is 90%. To do an emissivity test, place a strip of black electrical tape on the object while it is slightly hotter than ambient temperatures, measure the tape and then the actual object; if there is a temperature difference, adjust the emissivity so the object temperature equals the same readout from the electrical tape. Note the emissivity value for repeatable readings. A high temperature flat black paint can be substituted for the electrical tape. Also note your angle of measurement, 90 degrees to your object is best to avoid reflected temperatures from surrounding objects that will effect your reading.
Make sure any IR Radiometer has correction for Emissivity, covers the appropriate temperature range you need and has the spot size to distance ratio clearly stated. A built-in laser pointer is not as accurate as one would assume because it is not designed to paralex the same field of view as the IR detector but is a worth while approximation.

Thank you for asking this question as to what IR Radiometer to purchase; finally, something on the forum I can answer

 

[stormchaser]

Infrared Thermometers (IR Radiometers) all have a spotsize to distance ratio and minimum spot size resolution. For example, if minimum spot size is 1", the detector recieves all emittance in a one inch circle and computes it average temperature. Now, if the radiometer has a spot size to distance ratio of 5:1, that means at 5 inches away from the object it measures the average temperature of a 1" circle on the surface, at 10 inches away it measures the average of a 2" circle and at 4 feet away it is measuring a 9.6 inch circle; this definitely will effect accuracy and reatability. The higher the ratio, (examples 30:1, 60:1, 90:1) the greater the resolution of the detector, allowing you to measure small objects at greater distances. This is what effects pricing on various models in combination to the detector's temperature measurement range (example -20 to 200 deg. F.)
Realizing the effect on accuracy this spot size to distance ratio has and knowing what your needs are will help select the appropriate model, pricing and effective use of the various models in the market place.
Also, emissivity must be concidered as all objects do not radiate their heat the same. All objects above absolute zero emit heat, that is what IR is measuring, but nothing emits 100% of it's heat. Emissivity is a percentage of that emittance; example 0.90 is 90%. To do an emissivity test, place a strip of black electrical tape on the object while it is slightly hotter than ambient temperatures, measure the tape and then the actual object; if there is a temperature difference, adjust the emissivity so the object temperature equals the same readout from the electrical tape. Note the emmisivity value for repeatable readings. A high temperature flat black paint can be substituted for the electrical tape. Also note your angle of measurement, 90 degrees to your object is best to avoid and other reflected temperatures from surrounding objects that will effect your reading.
Make sure any IR Radiometer has correction for Emissivity, covers the appropriate temperature range you need and has the spot size to distance ratio clearly stated. A built-in laser pointer is not as accurate as one would assume because it is not designed to paralex the same field of view as the IR detector but is a worth while approximation.

Thank you for asking this question as to what IR Radiometer to purchase; finally, something on the forum I can answer

Can you recommend a specif model under $100 or am I being too cheap?

 

[SportFishCruising]

Here is one link of many available googling 'infrared thermometer'.
http://www.infraredthermometersale.com/
I am not affliated with them, I provide it only because you asked for referals of <$100 and theirs start at $75US plus their website explains everything I stated in my above post.
Having read their website (briefly) I like the ST 642 ($75) because it has an optional K-Type Thermocouple ($15) which will be great for doing the emissivitiy tests without the electrical tape or high temp paint. LOL..you don't wanna put black paint on those glossy white DD's now...do ya!
Make sure you understand it's spotsize and temperature range specifications and it will perform nicely for you.

 

[REBrueckner]

Post #9 has the right idea...measure and record the temperatures of different components and compare port and starboard as well as annual readings.

If you also put a thin strip of dymo tape on your instruments to mark normal readings at your normal cruise RPM, you can make much faster visual scans of all instruments to be sure things read normal there.

 

[GJH]

Ditto on the electrical temps, I also do the batteries now and then, though a couple of the banks have temp sensors on the chargers. While I haven't pointed the IR at them, I give a feel to to the shore power connections on a daily basis too.

Agree too on the beer. We prefer bottled, and one of our beverage cooler/reefers is a little erratic so taking regular temps would be the sensible thing to do. When appropriate coldness is detected, drinking needs to follow immediately.