evac User Manual March 2014 Prepared by: Gareth Wilson and Sinethemba Mngomezulu

evac User Manual March 2014 Prepared by: Gareth Wilson and Sinethemba Mngomezulu

evac User Manual Page 1 TABLE OF CONTENTS LIST OF FIGURES... 2 1. ANATOMY OF THE EVAC... 3 1.1. Basic principles... 3 1.2. evac frame... 4 1.3. Electric controls... 4 1.4. Motor and vacuum pump... 5 1.5. Moisture trap... 6 1.6. Vacuum cylinder lid... 7 1.7. Vacuum cylinders... 8 1.8. Hoses... 9 2. EFFECT OF SLUDGE CONSISTENCY ON DESLUDGING METHOD... 10 2.1. Free flow method... 11 2.2. Plug and gulp method... 11 3. TRASH... 12 4. ACCESS... 13 5. SET UP... 15 6. PERSONNEL NEEDED... 16 7. OPERATING THE VACUUM VALVE... 17 7.1. Controls... 17 7.2. Sludge hose... 18 7.3. Cylinder... 19 Filling the cylinders... 20 8. MOISTURE TRAP... 21 9. TRANSPORTING THE SLUDGE... 24 10. AFTER EMPTYNG THE PIT... 25 11. TROUBLE SHOOTING... 27 11.1 Low vacuum... 27 11.2 Blockage... 27 11.3 Dirty moisture trap... 27 12. MAINTENANCE... 28 12.1 Oil/lubrication... 28 12.2 Cleaning... 28 12.3 Moisture trap... 29

evac User Manual Page 2 LIST OF FIGURES Figure 1: Front View of the pump assembly... 3 Figure 2: Side View... 4 Figure 3: Top View... 5 Figure 4: Moisture trap design... 6 Figure 5: Vacuum cylinder lid... 7 Figure 6: Vacuum cylinder... 8 Figure 7: Sludge hose and air hose... 9 Figure 8: Effect of sludge consistency on desludging method... 10 Figure 9: Free flow method... 11 Figure 10: Plug and gulp method... 11 Figure 11: Sludge suction hose blockage... 12 Figure 12: evac in narrow path... 13 Figure 13: evac on steep slope... 13 Figure 14: evac on steps... 14 Figure 15: Set up of evac... 15 Figure 16: Operating the evac and hose... 16 Figure 17: Carrying a cylinder... 16 Figure 18: Air valve open and Figure 19: Air valve closed... 17 Figure 20: Pressure applied to the cylinder lid... 18 Figure 21: Vacuum lid... 19 Figure 22: Moisture trap... 19 Figure 23: Operating the vacuum cylinders... 19 Figure 24: Float valve (left) and cross section (right)... 20 Figure 25: Ideal sludge level in full cylinder... 21 Figure 26: Moisture trap... 21 Figure 27: Moisture trap (cross section)... 22 Figure 28: Moisture trap valve open and Figure 29: Moisture trap valve closed... 23 Figure 30: Operators carrying a full container... 24 Figure 31: Operators transferring sludge to a larger container on a waiting truck... 24 Figure 32: Cleaning the evac... 25 Figure 33: Sludge hose end caps... 26 Figure 34: Inside the vane pump... 28 Figure 35: Cleaning of moisture trap... 29

evac User Manual Page 3 1. Anatomy of the evac Suction connection Vacuum gauge Moisture trap Oil reservoir Vane pump Belt guard 1.1. Basic principles Figure 1: Front View of the pump assembly The evac is designed to access the most difficult locations and most restricted pits. It uses a small vacuum pump to create a vacuum of approximately 0.7 bar in a 47 litre vacuum tank 0.9 bar max). The evac has three main parts: the pump assembly, the vacuum hose, and the vacuum cylinder, each of which can be carried by just one or two people. The vacuum force produced by the evac is no different to that produced by a large vacuum tanker, for while the drive motor is only rated 1.5 kw, this is nevertheless powerful given the size of the vacuum cylinder. The vacuum cylinder is purposely kept small a) to ensure a vacuum can be developed quickly (the larger the cylinder, the longer it takes to produce a vacuum), and b) so that it can be carried over any terrain. The evac is powered by an electric motor which means an electricity supply or a generator is needed.

evac User Manual Page 4 1.2. evac frame The controls, motor, vacuum vane pump, oil reservoir and moisture trap are all mounted on a two wheeled trolley frame. The total weight of the frame is 60kg. It can be wheeled to site or carried across rough terrain if necessary. Vacuum camlock connection Vacuum gauge Pressure gauge Drive belt Figure 2: Side View 1.3. Electric controls The evac requires a 240V electric power supply. The switchgear is located in the box mounted on the top of the motor. The ON/OFF switch is located on the side of this box.

evac User Manual Page 5 1.4. Motor and vacuum pump The vane vacuum pump is powered by a 1.5kW electric motor via a drive belt shown in Figure 1 inside a protective cage. 15 m power cable with 3 pin plug Exhaust port Moisture trap Motor Motor control box with on/off switch Motor Pressure gauge Vane pump Figure 3: Top View

evac User Manual Page 6 1.5. Moisture trap It is important that no moisture or sludge enters the vane pump. The moisture trap is designed to catch and contain any moisture in the suction line before it gets into the vane pump. However, if enough fluid is drawn through the suction line some moisture may get into the vacuum pump, which must then be stripped and cleaned (see section 12). Figure 4: Moisture trap design The large diameter of the moisture trap ensures that the incoming air is greatly slowed down, which allows liquid droplets in the air flow to drop out of suspension and fall to the bottom of the trap. Note that if the trap becomes full of liquid it will no longer function as intended. To prevent this occurrence, the ball valve at the bottom of the trap must be opened (only when the motor is switched off!) to allow any liquid that has accumulated to drain out. This is described in more detail in Section 8.

evac User Manual Page 7 1.6. Vacuum cylinder lid The vacuum cylinders have one custom made lid, which is shared between the cylinders. The vacuum lid has connections for both the airline from the moisture tap and for the sludge hose which is positioned in the pit. The airline is fitted with an air valve, which when closed (i.e. in the horizontal position) seals the vacuum cylinder and is used as the main operating control during pit emptying. Vacuum release valve Air hose connection Sludge hose connection Figure 5: Vacuum cylinder lid Primary valve float Note that the lid requires no bolts to seal in place on top of the vacuum cylinder. The inside of the lid is fitted with a high density foam rubber seal. When the lid is pushed firmly down on top of the cylinder while simultaneously the vacuum pump is switched on, the formation of the vacuum in the cylinder pulls the lid down onto the seal allowing the vacuum to increase to operating level (>0.6 bars, usually). If the foam rubber seal becomes worn or soiled it will no longer function properly and should be cleaned or replaced.

evac User Manual Page 8 1.7. Vacuum cylinders The evac is supplied with three custom made vacuum cylinders which are used to collect the sludge and transfer it to either a disposal pit or to a vehicle with larger sludge containers for offsite disposal. Vacuum lid Vacuum cylinder Handles Figure 6: Vacuum cylinder

evac User Manual Page 9 1.8. Hoses The evac comes with two hoses: a 3 metre long 25mm diameter airline to connect the vacuum lid to the moisture trap and a 3 metre long 75mm diameter sludge hose. The airline provides adequate leeway to position the vacuum cylinder close enough to the pit that a minimum of suction hose is required to still access the pit. The sludge hose is supplied with an end cap for transport between pits to prevent any sludge which remains inside the hose after operations from contaminating the surrounding area or the transport vehicle. The length of the sludge hose provides adequate length to reach up to 2 metres below ground level, below which emptying is not feasible and should not be necessary (although the hose can be easily enough extended using the end cap coupling provided). Sludge hose end-caps one male, one female 3m airline 3m sludge hose Figure 7: Sludge hose and air hose

Not Suitable <50 l/min Rate of Emptying 5-10 l/s evac User Manual Page 10 2. Effect of sludge consistency on desludging method The method used for emptying pits with the evac depends on the consistency of the sludge, which can vary from very wet to wet, thin, thick or dry, as shown below. Very Wet Sludge Very wet sludge - mostly water Use Free Flow Method Rate of 10 l/s Time to fill a cylinder 5 seconds Wet Sludge Wet sludge watery with high suspended solids Use Free Flow Method Rate of 5 l/s Thin Sludge Thin sludge flows well Use Free Flow / Plug & Gulp Method Rate of 100 l/min Thick Sludge Thick sludge very slow flow Use Plug & Gulp Method Rate of 50 l/min Dry Sludge Dry sludge does not flow Not suitable for evac Figure 8: Effect of sludge consistency on desludging method The free flow method is best suited for wetter sludges, while the plug and gulp method is more effective for thin and thick sludge. The evac is not suitable for removing relatively dry or stiff sludge. The rate of emptying varies depending on the consistency of the sludge as well, with thin and thick sludges taking more time to suck out than wet sludges. The difference between the free flow and plug and gulp methods are explained in sections 2.1 and 2.2 below.

evac User Manual Page 11 2.1. Free flow method Figure 9: Free flow method The free flow method uses the suction created by the evac and the natural flow of the sludge toward the hose to fill the vacuum in order to empty the pit. The sludge hose can be left in the pit and requires little movement to aid the flow of sludge. 2.2. Plug and gulp method Figure 10: Plug and gulp method The plug and gulp method is a standard method used by vacuum tanker operators (regardless of the size of their equipment) to remove thicker sludge from pits. Thick sludge does not flow quickly into the void created by the sludge that has been suctioned up, as is the case with thinner sludge. With the plug and gulp method, the hose operator moves the sludge hose in and out of the sludge and around the pit to aid the flow of sludge into the hose. When the hose is lifted out of the pit the full vacuum can be applied to moving just that portion of sludge, which then moves more easily. Operators also find that it helps to bang the hose on the side of the pit to encourage the sludge to keep moving up the pipe.

evac User Manual Page 12 3. Trash Pit latrines often contain a range of non-faecal material which may pose a risk of blocking the suction hose when the pit is emptied. The coupling fitted to the end of the sludge suction hose will ensure that if the hose does become blocked, the blockage will be at the hose opening and not further up. In the event of a blockage, remove the hose from the sludge to inspect the blockage, open the air valve on the vacuum lid to release pressure, and use a hand tool to remove the object. Figure 11: Sludge suction hose blockage

evac User Manual Page 13 4. Access The evac is designed to empty pits which are inaccessible to larger vacuum tankers. To facilitate this, it is made up of portable components that can be carried by two or more people. The trolley can be pushed to most sites and can be manoeuvred along narrow paths, down steep slopes and up steps. See figures 12, 13 and 14 for examples of the kind of terrain which can be negotiated. Figure 12: evac in narrow path Figure 13: evac on steep slope

evac User Manual Page 14 Figure 14: evac on steps

evac User Manual Page 15 5. Set up For ease of use, the set-up of the evac should allow the operators to empty the pit efficiently without being hindered by the location of the equipment. As the sludge hose is 3 metres long, in order to allow for 2m depth in the pit the cylinder should be positioned within 1 metre of the pit. The cylinders should be positioned close together on a level surface. As the lid will be moved between cylinders, enough slack should be allowed for both the air hose and the sludge hose to allow the lid to be lifted off one cylinder and placed on the next one (see Figure 16). The evac pump assembly should be positioned a short distance away from the pit so as not to hinder access to the pit. As the air hose is 3 metres long, the pump assembly should be positioned within 2.5 metres of the cylinders to allow for the movement of vacuum lid. Figure 15: Set up of evac

evac User Manual Page 16 6. Personnel needed The evac is designed to be used by 2 or 3 operators. Typically, one person is required to operate the evac and vacuum cylinder switch and valves, one to operate the sludge hose and two to carry the filled vacuum cylinders to the disposal site or vehicle. This means that a two person team is the minimum workable number. Figure 16: Operating the evac and hose Figure 17: Carrying a cylinder

evac User Manual Page 17 7. Operating the vacuum valve 7.1. Controls The main control for the filling of the vacuum cylinders is the air valve on the vacuum lid (see Figures 18 and 19). This valve should be open at all times except when the cylinders are being filled. Closing this valve seals the system, allowing the sludge pipe to have full vacuum power. Figure 18: Air valve open Figure 19: Air valve closed

evac User Manual Page 18 7.2. Sludge hose To prevent the cylinder from toppling over during pit empting under the combined weight of the sludge hose and the sludge in the hose, the cylinder operator should hold the cylinder upright and push down lightly on the lid of the cylinder (see Figure 20). Figure 20: Pressure applied to the cylinder lid

evac User Manual Page 19 7.3. Cylinder As pit sludge varies in density and water content the rate of emptying will also vary. Wetter sludge can be vacuumed much faster than thicker sludge. Very wet sludge can fill a cylinder in 5 seconds while drier sludge can take up to a minute. Because of such variable filling rates, careful attention needs to be given during operation to avoid overfilling the cylinders. Figure 22: Moisture trap Figure 21: Vacuum lid Figure 23: Operating the vacuum cylinders

evac User Manual Page 20 The vacuum cylinders are semi-transparent and therefore the level of the sludge inside is partially visible. The operator will know when the cylinders are full by monitoring this level. However as the operator gains experience with the evac it will become easier to gauge the filling of the cylinders by the weight of the cylinder as it fills. In over to prevent the cylinders being overfilled, a float valve is attached below the airline in the vacuum lid (see Figure 24). When the sludge level reaches the float valve it lifts the small rubber float which is located inside the guide tube (note - a squash ball has the right characteristics for this float, whereas a light ball like a ping pong ball is too easily lifted up by airflow during normal operation). When the level approaches the top, the float ball is sucked towards the air hole and prevents sludge from traveling further. When this occurs there is a noticeable change in the sound made by the evac due to the increase in vacuum pressure, and the operating valve on the cylinder lid should be immediately opened. Figure 24: Float valve (left) and cross section (right) Filling the cylinders Due to the turbulence of sludge entering the cylinder it is not recommended that the cylinders be completely filled, as this can cause sludge to enter the airline before the float valve is fully shut. It is best practice to partially fill the cylinders to around 35-40 litres (i.e. below the level of the top handles), as shown in Figure 25.

evac User Manual Page 21 Figure 25: Ideal sludge level in full cylinder 8. Moisture trap Figure 26: Moisture trap

evac User Manual Page 22 The second protection against moisture entering the vane pump is the moisture trap, located on the evac itself. It is designed to prevent moisture from entering the vacuum vane pump, which is not designed to handle moisture. The moisture trap is shown in detail in Figure 27. The moisture trap disperses the air flow over a larger area while forcing airflow to change direction. The combination of the greater flow area and the sudden change in direction is designed to remove suspended water particles from the air. These collect in the base of the moisture trap, while the dry air flows into the vacuum pump. Figure 27: Moisture trap (cross section) The moisture trap has a transparent mid-section which allows the operator to view any liquid that is collecting. It is advisable that the operator always checks the moisture trap for accumulated liquid before the filling of a new cylinder commences. When liquid has collected in the moisture trap, the ball release valve in the base should be opened to allow the liquid to leave the trap and closed again once the trap is empty. Figures 27 and 28 show the valve in the open and closed positions. The liquid in the moisture trap should be considered contaminated. It therefore should not be released into the surrounding area, but collected in a small container and disposed of along with the sludge.

evac User Manual Page 23 Figure 28: Moisture trap valve open Figure 29: Moisture trap valve closed If the clear window on the moisture trap becomes soiled, the base of the trap should be released and both the top and bottom parts of the moisture trap should be cleaned. If this occurs often, it is likely that the cylinders are being filled too high and sludge is being sucked through the airline.

evac User Manual Page 24 9. Transporting the sludge The vacuum cylinders are designed for carrying sludge a short distance: either to a nearby disposal pit or to a vehicle with larger, sealed containers. The cylinders are designed to be carried by two operators. They have fixed handles at both the top and the bottom for easy carrying and emptying. Figure 30: Operators carrying a full container Figure 31: Operators transferring sludge to a larger container on a waiting truck

evac User Manual Page 25 10. After emptyng the pit When emptying is finished, there may be some sludge left inside the sludge hose. It is important to leave the sludge pipe inside the pit before release the suction by opening the air valve in the vacuum lid. Shake the sludge hose to loosen any solid material left on the inside of the hose first before lifting the hose out of the pit. As the sludge hose will be contaminated after use, it is important that it is placed in a large sack or other dedicated receptacle when it is not in the pit, as placing it on the ground will contaminate the environment. Cleaning the evac The evac hose and cylinders will be covered in sludge, and therefore require cleaning before leaving site. To do this, use a large drum filled with water to flush the pipe. Figure 32: Cleaning the evac Place the sludge hose in the water drum and scrub down the exterior of the hose with a dedicated cleaning brush while it is submerged in water. Once the outside is clean, use the evac to flush the inside of the hose and cylinders. By sucking water into the cylinders from the drum the cylinders can be also cleaned. They will still, however, be faecally contaminated.

evac User Manual Page 26 The suction hose is supplied with end caps that clamp onto the inlet and outlet of the sludge pipe for transportation. This will prevent any sludge in the pipe, or water that has been used for cleaning the pipe, from spilling. Figure 33: Sludge hose end caps

evac User Manual Page 27 11. Trouble shooting 11.1 Low vacuum If the vacuum gauge attached to the moisture trap (see Figure 2) shows a vacuum below 0.6 bar, check all airlines for loose connections and seals. If the problem persists, check the vane pump as shown in Section 12. 11.2 Blockage Pit latrines may contain various types of trash which can block the sludge pipe. A sudden increase in vacuum, which will be noticeable on the vacuum gauge and also from the sound produced by the evac pump exhaust, may indicate that the sludge pipe has become blocked by foreign material at the hose inlet. Release the vacuum valve on the lid and inspect the sludge hose. 11.3 Dirty moisture trap If the cylinders are filled too high, sludge can be sucked through the airline into the moisture trap. Firstly, clean the moisture trap as shown in the maintenance section (Section 12), then reduce the amount of sludge filling the cylinders.

evac User Manual Page 28 12. Maintenance 12.1 Oil/lubrication The oil reservoir (see Figure 1), will require occasional topping up with vacuum oil. The correct specification of oil can be obtained from the nearest DeLaval (dairy equipment) supplier. A five litre can of oil should last for several years. 12.2 Cleaning The cylinders, lids, vacuum lid and sludge hose will require cleaning at the end of each day (see Section 10). The sludge hose and cylinders can be cleaned by using a dedicated large water drum. The outside of the sludge hose can be cleaned inside the drum and the inside by sucking water through into the cylinders. This can be done for each of the cylinders. Dirty water can be disposed of along with the sludge. The vane pump will require cleaning if moisture or sludge enters it as a result of improper use of the evac. The evac should be disconnected from the power source and the mounting bolts and air hoses should be detached in a clean environment. The side cover of the vane pump can be removed to access the internal disks and axle. Figure 34: Inside the vane pump If the disks have become soiled, remove the centre axle and disks and clean with warm soapy water. Scrub away all dirt particles and rinse well before applying a coat of vacuum oil and reassembling.

evac User Manual Page 29 12.3 Moisture trap If the moisture trap becomes soiled, remove the moisture trap base by unbolting the strap located on the base of the moisture trap. The base should slide out and any liquid and particles can be disposed of with the sludge. Thoroughly clean both the upper and lower parts of the moisture trap. A pipe cleaner brush can be used to clean around the air inlet and outlet. Care should be taken to avoid any moisture entering the vane pump. Figure 35: Cleaning of moisture trap