When improving an icebox
in a boat’s mobile refrigerator
there are always difficult questions to answer like, type and how much insulation
or should condenser be air or water cooled. Another question, what would be considered as a correctly install compressor condensing unit for best performance.
A boat refrigerator’s insulation is considered inadequate if insulation exterior temperature is more than 4 degrees colder than cabinet ambient air temperature when refrigerator
has operated for a day or more. As mobile refrigerators are exposed to changing temperatures moisture in cabin
air can penetrate and collect in open spaces of insulation. Any insulation that allows air to move in and out as compressor cycles off and on will act as a dehumidifier collecting water reducing insulation efficiency. Closed cell R 20 to R40 insulation is commonly used in mobile refrigeration
. Even with closed cell material a complete moisture barrier is a good idea in boat refrigerators. Open cell insulation is used in heating
industry and may not be suitable for refrigerators.
Correct way to install a compressor condensing unit is in a location where cooling medium air passes through condenser coil only one time. Cabin ambient air will provide a more stable refrigerant operating pressures than water cooling. Pictures posted by Sumner and Celestialsailor show two of the best ways to install small Danfoss compressor condensing units. Ambient cabin air is drawn from coolest part of cabin through condenser and and fan attempts to pressurize that compartment forcing warm air out holes where warm air rises away condenser inlet.. This warm air rises mixing with cabin air adding no more heat to cabin than heat of one person would on a warm day.
What about question of condenser fan noise
There are two causes of fan noise with muffin fans, vibration and blade tip pulsating air sound. Vibration can sometimes be eliminated by placing soft washers between fan and condenser. Blade tip air noise can be absorbed by placing scraps of carpet to walls inside condensing unit compartment.
If I am building or improving refrigerator box what about toxic vapors from materials I use? Will these toxic vapors out gas over time causing health
I am not qualified to answer questions about Air Quality of gases. I know that any place that sells materials must provide you with a Material Data Safety
Sheet. Best you contact manufacturer of insulation and get MSDS paper on that insulation and other materials used.. As I recall
material in air with a TLV of less than 100 will kill and over time, diesel fuel
fumes with a TLV of 1000 is not good. I fond info on internet
Threshold Limit Values or TLVs are air quality standards developed by the American Conference of Governmental Industrial Hygienists. They are the model for many other air quality limits such as OSHA's permissible exposure limits (PELs).
TLVs are the amounts of chemicals in the air that almost all healthy adult workers are predicted to be able to tolerate without adverse effects.
There are three types:
• TLV-TWA (TLV-Time-Weighted Average) which is averaged over the normal eight-hour day/forty-hour work week. (Most TLVs.)
• TLV-STEL or Short Term Exposure Limits are 15 minute exposures that should not be exceeded for even an instant. It is not a stand alone value but is accompanied by the TLV-TWA. It indicates a higher exposure that can be tolerated for a short time without adverse effect as long as the total time weighted average is not exceded.
• TLV-C or Ceiling limits are the concentration that should not be exceeded during any part of the working exposure. Unless the initials "STEL" or "C" appear after "TLV", it is the eight-hour TLV-TWA that is meant.
TLVs are NOT "safe" limits. Even a few "healthy adult workers" will be unable to tolerate concentrations at the TLV.
TLVs also do not apply to people with certain health
problems, allergies, people taking certain medications or drugs, people who work longer than eight hours per day, children
or the fetus.
TLVs are not static - they change. They represent the current
best estimates based on research
. Make sure you have an up-to-date MSDS. Check the revision date.
TLVs are not available for all chemicals (There are ~700 TLVs. OSHA estimates there are over 650,000 chemicals in the workplace. Many have never been studied. Chemicals without TLVs or other exposure limits should NOT be considered safe.)
TLVs are used to assess workplace exposure by providing a comparison point for testing and to assist in product selection. When deciding which product to use, choose the chemical with the higher TLV so long as the chemical characteristics match your needs.
A lower TLV means less is allowed in the workplace air, and less you should inhale.
If you must use a chemical with a low TLV, make sure you plan adequate control measures (e.g., use in a chemical fume hood
or with adequate local exhaust
.) Make sure you arrange with EH&S for air monitoring if you suspect your exposure is not being adequately controlled.
TLV Measurement Units ContaminantUnitsUnit definition Dust, Fumes or Mist (solid particles)mg/m3Milligrams of contaminant per cubic meter of air. Gases and vaporsppmParts of contaminant per million parts