With regard to choosing a cracksealing machine there are several factors that are traditionally overlooked by contractors in favour of price and availability.
Like any piece of commercial construction equipment, the emphasis should be on production,material selection, reliability, ease of operation, efficiency/cost of operation, and safety factors.
To size a melter the following formula may be useful;
Heated Material Output = % Efficiency * Vat Size/Heat-Up Time
Many manufacturers will not provide you with a Heat-Up Time or an actual efficiency value, so it pays to ask current users of a machine their opinion, or go out and observe them.
A useful figure for Efficiency is 85%, any less and the unit will lack fuel economy and this may also indicate a substantial Heat-Up Time.
Example Calculation:
Heated Material Output = 0.85 * (265 US Gallons/ 1 Hour) = 225 US Gallons/Hour
Note, this is not pumped output, merely a realistic representation of what the material melting vat can do based on the available information. Also make sure you compare Actual Vat Volume, some manufacturers have high maintenance, submerged pumps which displace material.
A reputable manufacturer should also be willing to provide you a Theoretical Production Value for a pumping unit. This is based on material pump displacement and speed, plumbing size and configuration as well as hose type and size.
This number will generally be lower than what you calculate for melting capacity. Obviously you need to melt more than you can pump in order to maintain output. Always compare pump capacities.
Also to consider is the fuel type and size of the burners. Often a machine will have what appears to be tremendous production compared to rivals, only to find that the burner is significantly larger, and more costly to operate and maintain.
Superior Propane has some interesting information available on propane fuel consumption, including a Rule of Thumb. 24,000 BTU/hour uses 42 litres of propane/hour.
Propane is also fraught with safety and regulatory issues that need to be understood before buying a piece of equipment.
Most diesel burner machines will share a common, readily available fuel with the engine, and will be designed for an 8-10 hour work cycle. Again, a high BTU burner, and a unit that takes 2+ hours to warm up (without assitance) will use more fuel and may require more frequent filling.Typically this value will be between 10 and 15 litres/hour.
As for hoses, it is less important than the previous items, many customers are more than satisfied with non-heated hoses, and can be very productive with the right crew and organisation. Heated hoses are all but exclusively electrically powered, although more cumbersome methods have been tried in the past with engine coolant or HTO jackets to keep material flowing.
What you want to know is,
A)Can the temperature of the hose be controlled?
B)Does the hose sense/display actual temperature?
C) Does the hose have a diagnostic or failure indicator?
D) Is it lightweight yet rugged and flexible?
I hope that helps you and others to choose the machine that is right for their needs.
