Hot Tip #17 - Ironer Folder Drops
Like most problems in life, the cure will be obvious once we know the cause. Since we have the problem we can further deduce that the cause is not obvious; therefore let’s look at some not-so-obvious possible causes. Is the problem sporadic? The answer is obviously yes; otherwise, every item would be dropping. There are three “systems” incorporated in folders that could cause sporadic problems:
Mechanical, Electrical & Pneumatic.
Of these three, the least obvious cause is the Pneumatic systems. Check your air pressure. Install a large, four-inch, or larger, diameter pressure gauge at the folder. Watch the pressure closely; are there drops in pressure while the folder is off? If so, what is causing the drop? Look for the non-obvious possible causes. If the drop in pressure is slow to recover, we know two things: 1) the cause uses a lot of air. 2) The cause is for a long duration.
Areas to check:
A) Compressor capacity, is your compressor performing to its rating?
B) Air blow-down by maintenance or custodial departments.
C) Large air-driven pumps or motors, are frequently found in wastewater treatment systems.
If the drop in pressure quickly recovers we know two things: 1) The cause uses a lot of air. 2) The cause is for a short duration.
Areas to check:
A) Large diameter air cylinders, frequently found in rail lifts.
B) Solenoids installed on airlines for automatic blow-down; lint collectors are a good example. If you find this to be the problem, reduce the pipe size after the solenoid to ¼” soft copper and pinch the copper closed until it takes more than 3 minutes to fill the air receiver tank on the dryer. Air will not be needed until the next blow-down cycle, 15 minutes or more after the first cycle. Remember, if it was easy it would have been obvious and anyone could have solved it!
Hot Tip #16 - Air Leaks
While visiting laundries one issue frequently arises, how to handle compressed air leaks.
Most leaks that I find are very difficult to correct. The easy ones are generally corrected by facility maintenance long before I arrive. The easy ones are those that you find in the air delivery plumbing. Examples include: leaking quick disconnects, a pinhole in plastic airlines, leaks at pipe threads, etc.
Difficult leaks to correct are those internal to the air components such as: Air motors on chemical mixing tanks, air cylinders leaking through the piston or shaft packing, control valves blowing out the exhaust ports, etc. Many laundries have in excess of 50% of their total compressed air lost through leaks!
I was recently in a plant where a six-inch diameter, eight-foot stroke; air cylinder soil lift had a major leak. This horizontal cylinder was 18 feet above the floor, placed between the roof rafters. Maintenance stated that it would require four hours to disassemble and repair the cylinder. I was informed that the plant was running 20 hours per day, 7 days a week. There was “no way” to repair this major leak! So it remained to leak for years! This was a difficult leak to correct!
Amazingly, once it was determined that the soil lift leak was the cause of many of their ironer folder problems, a way was found to get it fixed within three days. It was later calculated that the leak had been consuming $120.00 per week worth of electricity.
Hot Tip of the week; install a solenoid valve on each piece of equipment that uses compressed air; folders, ironers, dryers, etc. This should be a three-way valve so that when de-energized it bleeds the machine of all stored pressure. Now your leaks will only occur while that specific machine is running.
Hot Tip #15 - Condensate Return Lines
All condensate lines should be pitched down 1/4" per 10 feet (5 mm/m) to allow for drainage of the condensate by gravity. The most efficient return systems are, by design, not completely full of liquid and are not vented to the atmosphere. They are referred to as dry-closed systems. They handle condensate at steam temperature (i.e. not sub-cooled). Condensate return lines are specified to carry a condensate load, in pounds of condensate per hour (kg/hr). In fact, some of the condensate flashes to steam in the relatively low-pressure return line. Because the volume of flash steam is so much greater than the volume of the condensate, the return lines actually carry about 96% to 99% flash steam by volume. Therefore, condensate return lines should be sized to maintain a reasonable velocity of flash steam (under 7,000 fpm/30 m/s) at an acceptable pressure drop for the specified condensate flow rate.
(from our friends at Armstrong Traps)
Hot Tip #14 - Pipe Sizing Factors
When determining pipe size for steam systems, the following factors should be considered.
Initial steam pressure: the output pressure at the boiler or the main for branch piping.
Allowable pressure drop: the total pressure drop allowed from the source to the end of the line. This includes all drops from line loss, elbows, valves, etc. Pressure drops are usually due to friction between the steam and piping. Pressure drops are usually measured in psi/100 ft. Pressure drops for the total system should generally be less than 20% of the boiler operating pressure.
Flow rate: the amount of steam that must be supplied to the heat exchangers connected to the steam lines. Flow rate is measured in lbs/hr.
Steam velocity: the speed of the steam flowing through the lines, in feet per minute. Erosion and system noise increase with velocity. In general, steam velocities in process steam systems should be maintained between 6,000 and 12,000 fpm with a maximum of 15,000 fpm.
Future expansion: lines should be sized with the foreseeable future in mind. When in doubt, remember oversized lines usually present fewer problems than undersized lines
Remember: When steam lines are too large, purchase, installation, and fitting costs increase substantially over the more appropriate smaller lines. Additionally, because their surface is greater, these larger lines waste more heat through radiation
(From our friends at Armstrong Traps)
Hot Tip #13 - Steam Traps
“Drain each drip point with a separate trap.”
This rule for trapping should never be broken under any circumstances. Short-circuiting occurs when the condensate outlets from two heat exchange units are connected. Short-circuiting is likely whenever the drip points of two heat exchangers are drained with one trap, even if the two units appear to be identical. Any differences in condensing rates will result in a variance in the steam pressure drops of the two units. The condensate from the unit with the lower pressure drop will prevent air and condensate coming from the other unit from reaching the trap. The difference in condensing rates can seem insignificant, but it is not insignificant and must be taken seriously. This means that every iron chest should have a separate trap. If it is a split chest design ironer then each half will have a separate trap.
I was troubleshooting an ironer problem over the phone several years ago where a GM was insistent that one of his ironers was not large enough to dry his goods. Maintenance assured me that the trapping system was working fine. Not able to solve his problem over the phone, I jumped on a plane to find an eight-roll Hypro iron with a single trap for all rolls!
Hot Tip #12 - Mud Legs
Dirt pockets, (mud legs) provide a low-flow area where dirt and scale can settle out of the steam and condensate stream. Dirt pockets must be cleaned out periodically and, therefore, should be part of a regularly scheduled maintenance program.
Some traps are more susceptible to dirt than others. Strainers should be installed before any trap that may experience problems. Some traps are available with strainers that are built in. If you use a strainer, (highly recommended) it must be blown down periodically. As with the cleaning of dirt pockets, this process should also be a part of a regularly scheduled maintenance program. For ease of blow down, a globe or ball valve can be connected to the blow-down port of the strainer.
Hot Tip #11 - Steam Trap Installation
Unions provide a simple means for removing traps from a system for repair or replacement. If one union is used, locate it downstream from the trap. A trap can be removed between the union and the next connection point upstream (shutoff valve, strainer, or drip leg). If two unions are used, place them either at right angles or parallel. Avoid placing two unions in-line in either horizontal or vertical piping. Two unions in line make it difficult to separate the trap from the rest of the system if the lines are well anchored
If your facility has a number of traps that are identical in size and type, such as with ironers, a great deal of downtime can be avoided by standardizing connections. Use the same length inlet and outlet nipples on all traps and supply them with the same fittings, including unions. Keep a standby trap with identical fittings as a spare. Whenever a trap tests poorly, the unions can be loosened, the standby trap substituted, and the original taken in for repair.
A by-pass valve that is inadvertently left open defeats the function of the steam trap. If continuous service is necessary, place a standby trap in parallel with the primary trap.
Hot Tip #10 - Steam Trap Repair
Every year, hundreds of millions of dollars worth of steam is wasted in the U.S. Much of this loss is at the expense of companies that have made a huge investment in energy management - only to fail to establish a program to maintain steam trap efficiency.
For $40.00, (less than the cost of one steam trap) a video from Armstrong Corporation is available to teach you how to “correctly” repair steam traps. This video is a great investment. I highly recommend it!
"Guidelines for Steam Trap Repair"
It offers an outline for the establishment of a plan for identifying faulty traps and returning them to effective operation. The first part of the tape provides guidelines to follow in the inspection and repair of any trap.
Hot Tip #9 - Latent heat of evaporation
One pound of water at 32 degrees F. plus 180 BTU’s = One pound of water at 212 degrees F. One pound of water at 212 degrees F. plus 971 BTU’s = One pound of steam at 212 degrees F. and at 0 PSIG. One pound of steam at 212 degrees F. and at 0 PSIG plus 46 BTUs = One pound of steam at 366 degrees F. and at 150 PSIG.
To one pound of water at 32 degrees, we have added a total of 1197 BTU’s to produce one pound of steam at 366 degrees F. and at 150 PSIG.
Out of the total 1197 BTU’s added, 971 BTU’s were required to change its state from liquid to vapor (81.1%). This is one of the reasons that steam is such a great conveyor of energy; but only if you convert the steam back into a liquid (condensate) in a useful process.
When you see steam exiting your washers this is not a useful process. You have not captured the 971 BTU’s (latent heat of evaporation) and you are wasting more than 81.1% of this available energy. “Steaming up” in a washer needs to be avoided as much as corporate taxes, swine flu, and traffic cameras! If you must steam up, reduce the steam rate of flow. The best way to do this is with a steam pressure-reducing valve.
Be aware that steam exiting your washers is a hazardous substance. Boiler treatment chemicals, which are present in this steam, are the most hazardous chemicals within most laundries. Some are class 4 carcinogens.
Hot Tip #8 - The Triboelectric Effect
Are you having ironing problems due to the triboelectric effect, also known as triboelectric charging?
This is a type of contact electrification in which certain materials become electrically charged after they come into contact with another different material and are then separated, such as through rubbing. The polarity and strength of the charges produced differ according to the materials, surface roughness, temperature, strain, and other properties. Thus, it is not very predictable, and only broad generalizations can be made. This property, first recorded by Thales of Miletus, suggested the word “electricity”, from the Greek word for amber, ēlektron. Other examples of materials that can acquire a significant charge when rubbed together include blended textiles when rubbed with other blended textiles.
As the Relative Humidity (HR) goes down, or your goods become too dry, this Triboelectric charging will increase. Static bar(s) installed on the ironer or the use of certain fabric softeners are the most common solutions. The most successful solution is to prevent your goods from becoming too dry before they enter the ironer. The wetter the goods entering the ironer the less TRIBOELECTRIC EFFECT you will encounter.