Dirt trap

Integral skinned These integral skin urethanes are designed to have an outer layer that is not foamed, with a foamed inner section. This provides a firm feel without the dirt trapping of the cut cells. Typical examples of this style are steering wheels and motor car fascias. 

Fouling. The downflow movement of liquid makes fouling a less severe problem with conventional internal circulation reboilers (Fig. 15. le) than with kettle reboilers. Fouling, however, can be severe if tubes are unflooded. The bathtub arrangement (Fig. 15.96) does not share the liquid downflow benefit, and fouling can be as much as a problem as with kettle reboilers. The isolating chamber forms a dirt trap, and must be blown down (e.g., by perforating the chamber floor). 

Some enduse applications involve parts that are subject to dirt or fingerprints. The breakdown of the smooth surface into a texture shadowed surface partially masks the dirt. Unfortunately it also contributes in the long run to dirt trapping which may defeat its original purpose. We need look no further than our computer keyboard to illustrate this point... 

The dirt traps AA002 and AA005 shall protect the sensitive needle valves AA003 and AA06 against blockages. With these needle valves, the flow volumes required... 

Finally, the inlet weir is also a dirt trap (like the recessed sump). So I would be afraid to use it in fouling or corrosive services. 

Below the downcomer of the bottom tray is the seal pan. The seal pan, like a recessed sump, is also a potential dirt trap. I ve crawled... 

Check that the abrasive is not contaminated with moisture, dirt, spent abrasive, etc., that the blasting equipment can deliver the abrasive at an adequate pressure and that the airlines are fitted with a water trap. 

Second, any valve which has been designed to operate on steam should not be expected to work at its best when supplied with a mixture of steam, water and dirt. A separator, drained through a steam trap, will remove virtually all the water from the steam entering the pressure-reducing set. The baffle type separators are found to be effective over a wide range of flow rates. 

Most plants are highly dependent upon their compressed air supply and it should be assured that the air is in at least reasonable condition at all times, even if the drying system is out of use for maintenance or repair. It is possible that the line condensation would be so bad that some air applications would be handicapped or even shut down if there were no protection. A vital part of the entire endeavor to separate water in the conventional compressed air system is also the trapping of dirt, pipe scale and other contaminates. This is still necessary with a dried air system. As a minimum, all branch lines should be taken off the top of the main and all feeder lines off the top of branch lines. 

Features should be arranged so that moisture and dirt are not trapped. Where this is not practicable consideration should be given to the provision of drainage holes of sufficient diameter, located so that all moisture is drained away (Fig. 9.14). 

Incoming gas may contain particles of dirt from within the circuit, especially on a new system. Suction strainers or traps are provided to catch such dirt and will be readily accessible for cleaning on the larger machines. 

The outlet pipe must always be from the lowest point, but may have a short internal upstand so that any dirt such as pipe scale or metal swarf will be trapped and not taken around the circuit. 

Piping circuits will usually contain a small quantity of dirt, scale and swarf, no matter what care is taken to keep these out. A strainer is fitted in the compressor suction to trap such particles before they can enter the machine. Such strainers are of metal mesh and will be located where they can be removed for cleaning. In some configurations two strainers may be fitted. 

Detergents aid the removal of dirt. Commercial synthetic detergents were first developed in the 1950s. Detergents act mainly on the oil-based films that trap dirt particles. Most detergents have an oil-soluble portion (usually a hydrocarbon chain), and a water-soluble portion, which is generally ionic. 

Flushing is performed on new piping to remove material that was trapped during construction. Typical materials include dirt, stones, and small pieces of concrete however, hardhats, lumber, and tools have been found during actual tests. 

The need for positively sealing the downcomer is determined in this phase. This could be achieved by installing an inlet weir, which is a weir installed at the tray inlet to keep the downcomer outlet immersed in liquid. A similar device, which extends below the tray floor, is a seal pan (Fig. 17). Both devices provide positive assurance against vapor rising up the downcomer, but they may also trap solids and dirt and cause blockage. A seal pan must always be used in the downcomer from the bottom tray otherwise there is nothing to prevent vapor from rising up the bottom downcomer. 

Quicklime (in the form of lumps) is periodically loaded with slusher 1 into apparatuses 2 for slaking the apparatuses are filled with technical water through vapour-heated shell-and-tube heat exchanger 3. Slaking forms lime milk and solid residue (cinder). The cinder is sent out of apparatuses 2 with facilities for forced unloading into transporter 4 lime milk flows down a chute into screw trap 5 and reservoirs 6. Small pieces of cinder are sent from the trap with screws to the transporter. The cinder in the form of dirt is transported into bunker 7 and periodically removed. Lime milk in reservoirs 6 is constantly mixed so that the suspension does not settle. The weight ratio of Ca(OH)2 is determined by the density of the sample of lime milk from the reservoirs it should be 10 - 18%. 

Heavier grades are used in construction and for covering boats, RVs, and snowmobiles. These products provide abrasion resistance and protection from water, dirt, dust, and sunlight. In addition, they "breathe," meaning that water vapor and air can pass through rather than being trapped on the inside. 

Flowmeters. Even after modification the pumps usually showed some long-time drift in the pumping velocity, mainly due to changes in valve operation caused by corrosion, dirt accumulation or trapped air bubbles. Thus all flowrates have to be measured at regular intervals and the pumps adjusted when needed. Various devices for flowrate measurements were tested and two were finally selected. 

In smaller water purification systems, we can often find a cartridge-type depth filter used for the particle removal. The cartridge is made of cellulose, cotton, or polymer fibers, which trap dirt particles throughout its volume. Once a cartridge reaches its holding capacity, it is disposed of and replaced by a new one. 

---