HYDRAULIC ELEVATOR CONTROL VALVES AND POWER UNITS by R. Kirk Muller, Production Manager, Maxton Manufacturing Co.

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1 Page 31 HYDRAULIC ELEVATOR CONTROL VALVES AND POWER UNITS by R. Kirk Muller, Production Manager, Maxton Manufacturing Co. Elevator control valves and power units have come a long way in a relatively short period of time. Environmental factors and technological issues have mandated rapidly evolving design of hydraulic elevators, which, in turn, has necessitated the development of superior hydraulic control valves. Most companies are renewing efforts toward improved quality assurance and preventative maintenance of their manufacturing equipment, which will pay dividends for us all if we develop rigorous industry-wide standards and procedures to improve maintenance and service to customers, and by promoting thorough understanding of various issues. Contamination The first step toward eliminating elevator failure due to contaminants in the system is to accept and understand that the hydraulic oil in the system is a vital component, requiring maintenance no less than any other key part of the system. Some contaminants frequently found in valves are a direct result of the elevator installation. Contamination can appear in many forms; the most common sources including welding slag, lint from rags, plastic stripped from wire and electrical tape. Teflon tape, improperly installed on pipe threads, will find its way like a magnet to the strainers of the control valve. Pipe turnings from threading and grooving field pipe, entering the system due to inadequate Tank Discharge Filter Educational Focus Compilation 31 Maxview Oil Viewing Device cleaning of the inside of the pipe following machining, will cause control valves to malfunction and will do irreparable damage to the pump. Not all contaminants, however, are a direct result of the elevator installation. Often, during the storage of a unit and/or the installation process, other trades working in the vicinity of the elevator equipment contaminate open pipes and tanks with debris that can cause early system failure. Another frequent source of contamination, from allowing components to run-to-failure, is the elastomer noise-dampening bladders or inserts degrading and coming out of the silencers (mufflers). Whether it is a new installation, modernization or normal maintenance, contaminated systems must be addressed. Purging the system is not always as easy as prevention might be. Sealed tanks with operable tank breathers and filtering the oil from the pit can or oil return line are a major step toward preventative maintenance. To facilitate this procedure and help determine what lies at the bottom of the tank, Maxton has developed the MaxView Oil Viewing Device. Simply pull a sample of oil from the bottom of the tank, analyze the sample and thoroughly clean the system if necessary. Upon cleaning the tank, it is important to filter the oil, wipe out the tank and ensure that other contaminants are not present before refilling the unit with oil. Toward that end, spraying the inside of cleaned-out tank with oil, and using a small squeegee to push all the oil to an accessible corner for removal, will ensure that lint from the cleaning rags will not cause an embarrassing failure. Another service aid for assuring the quality of the oil in the system is a tank discharge filter an inexpensive means for continually filtering the oil and helping to prevent contaminants from recycling through the pump, valve and jack. Modernization There are too many units running with obsolete equipment, which, upon failure, could prove costly in either downtime or the resultant liability from injury. In 1995, the Massachusetts Department of Public Safety published a letter regarding a problem with Esco valves. To date, we still get frequent calls for parts availability for these valves. Jobs with other obsolete valves should be modernized with new and serviceable components. We declared the UC3 control valve obsolete in 1988, yet many of them are still installed and running. UC3 valves have had a long and

2 Page 32 useful service life but should now certainly be replaced. The cost of a direct-piping replacement UC4 and the time for installation are minimal. Getting away from the run-to-failure mode will provide better service and performance and limit the exposure from liability. This current period in the business cycle as the economy squeezes the profit margin from new construction presents significant opportunities for companies in the modernization market. Other considerations when performing modernizations should be in the serviceability and safety of the installation. When replacing an obsolete under-tank control valve that requires some degree of re-piping, consider re-positioning the valve above the tank, thereby eliminating the need for tank shut-off valves to perform control valve maintenance. This also provides a much safer condition for the mechanic, away from turning belts and sheaves, during valve adjustment. Another safety concern of modernizing a unit is the elimination of pump-loop connections. Many elevators are operating with the discharge line from the valve tied into the pump suction line. This type of arrangement lends itself to the potentially dangerous situation of super-heating the oil and should be re-piped for direct valve to tank discharge. The advent of the submersible pump/motor has reduced the size and cost of power units, creating as a viable option the complete change-outs of older tank units with new, submersible power units. Different piping configurations are often necessary to facilitate installation, however, often the wrong valve is initially ordered and must later be exchanged, resulting in job delays and unnecessary additional costs. When surveying a job for valve replacement, it is therefore important to be aware at this beginning stage what options are available. (For example, the UC4 valve has the jack connection to the right with the tank to the left and the UC4M is a mirror of that with the jack to the left and the tank to the right.) MAXIMUM FLOW SCH 80 PIPE GPM 2" /2" 3" 412 4" 717 Pipe size is another important consideration during modernization. Older valve systems sometimes required back pressure on the discharge line, while newer valves perform better with little or no back pressure on the discharge line. The discharge line, and all of the field piping, 32 Educational Focus Compilation s UC4 Valve UC4M should be evaluated to determine if it is adequately sized. Maxton recommends that fluid velocities not exceed 20fps. Using 20fps as a rule, the following maximum flows can be determined. Maintenance The maintenance of a Maxton hydraulic control valve should be one of the easier tasks for the experienced mechanic. If constant re-adjustment is required, something is amiss because this shouldn t be! This is a symptom of a system problem that needs to be evaluated and corrected. Rebuilding control valves is a task best accomplished by the manufacturer. The valve should be completely stripped, re-assembled with current production components and properly tested. Trying to do this in the machine room, re-using fatigued or worn components and testing and/or troubleshooting due to assembly errors, on your customer s elevator, is not a very good use of time and money. Maxton Online We encourage all elevator professionals to visit our newly-upgraded website at and use the many useful tools we have added. These include Engineering Data, a Valve Calculator to assist in valve sizing, detailed Product Information, as well as complete downloads of the Maxton catalog. Once registered on the site, you can easily order online the proper valves and support products for your jobs, including re-conditioned valves through the Valve Exchange Program. c

3 Page 33 UNITIZED HYDRAULIC CONTROL VALVES by Abe Salehpour and William Lawrence, Elevator Equipment Corp. Throughout the elevator industry, the name Elevator Equipment Corp. (EECO) has meant elevator control valves since Most independent elevator contractors cut their eye teeth on EECO brass valves during the days of the 1950s and 1960s until the advent of the unitized UV-5 combination control valve. The basic design of this valve has contributed to its acceptance by the industry and to its longevity, having completed over 30 years of performance with little exterior changes. Educational Focus Compilation 33 Since its introduction in 1970, the UV-5 unitized hydraulic control valve has been the mainstay of EECO s product line. Over the years, a number of modifications have been made to this valve with replaceable sleeves (UV-5A), temperature/ viscosity compensation (UV-5AT) and both temperature and pressure compensation (UV-5ATC). Internal improvements have also kept pace with seals and O-rings upgrading to Viton as standard for improved high temperature performance. An innovative feature of the UV-5 is its pump inlet mount consisting of a clamp ring bolted to the body with high tensile socket head cap screws, which ring captures the pipe fitting itself. This arrangement serves a dual purpose. First, it allows for a variety of steel fittings to suit whatever type of fitting the pump unit manufacturer requires, and second, the cap screws allow for swiveling the valve in any direction to accommodate alignment without the necessity of a pipe wrench. Installation into an existing pump unit as a retrofit is straight forward, either under the tank or in the tank. The only consideration is the number of operating solenoids (coils) used on the older unit versus the four required for the UV-5. Generally, an upgraded controller is supplied in a modernization with the necessary upgrading of the hoistway signal equipment. Considering that two-way leveling has been in use for more than 30 years, there should be very few one-way leveling systems in existence. An important consideration to address when installing a new system is where to place the pressure gauge so as to read the maximum pressure seen by the motor. The required horsepower is a direct function of the maximum hydraulic pressure sensed by the motor. Two things affect this pressure, the gross load on the elevator platform and the internal resistance of the hydraulic system itself. The gross load is easily calculated having known parameters. However, the system resistance is an unknown. While many factors enter into the picture, an accurate pressure gauge is a most valuable tool. Starting with the cylinder and piston assembly, we encounter packing friction, and in the case of slipper guides, rail/car friction. Next, there is the piping system itself with elbows and valves causing restrictions and internal friction from fluid viscosity. The control valve itself demands a loss so as to effectively use the differential pressures therein to operate. Let s take for example a system having a 2in. schedule 80 pipe as the main line to and from the cylinder. At approxi-

4 mately 180gpm, the frictional loss is a little more than 0.5psi/ft at a line velocity of 20fps. Fifty feet of pipe would have a loss of approximately 25psi. Add to that the 90 elbows, say five, each of which have an equivalent loss of five feet, (approximately another 12psi) for a total of 37psi. Now, the loss through the check valve, which has a spring load on it, may be as high as 50 to 100psi, let s say 50 on the low side, so now there is a total loss in the hydraulic system of 87psi that adds to the pressure provided by the gross load. For example, if the pressure measured at the cylinder (down in the pit), while the car is traveling up, near the top landing, is shown to be, 300psi, the pump pressure would be approximately 387psi. These calculations are done at the engineering stage. Knowing what is required of the motor, we can now set the relief valve. American Society of Mechanical Engineers (ASME) A17.1 Rule 303 states that the pressure relief valve may be set up to 150% of the working pressure measured at the valve. Today s unit valves have pilot-operated relief valves, instead of direct-operated types. The difference between these two types is this: Direct-operating relief valves consisted of a spring-loaded valve seated against the pump pressure and held closed by the action of a very strong spring. When the cracking pressure was reached, the valve began to open. However, since the strong spring had to compress more and more as the valve opened to relieve the total discharge from the pump, the force against the valve increased resulting in a pressure rise also. The code authorities recognized this and allowed for a 20% rise from the cracking pressure to compensate for this action. Pilot-operated relief valves do not require this rise, as they open at the set pressure and either hold that pressure or drop the pressure slightly as the by-pass valve unloads (opens), allowing full pump output to discharge back to the reservoir. The system pressure measured at the cylinder port of the valve will take into account the pipe and system friction losses, but not the check valve loss so, using figures from the preceding example, the system pressure at the valve cylinder port should be approximately 337psi. The pump pressure is 387psi, which is 387 times 125% and equals 484psi. Allowing the pressure to rise another 20% to 150% of working pressure allows the relief valve to be set to open at a maximum of 580psi. Local codes must be adhered to. EECO valves may be equipped with fittings of the quick-disconnect type that allow for the exchanging of 34 Educational Focus Compilation pressure gages from the cylinder port to the pump port without the use of tools. This is important when setting the relief pressure because when the system dead ends, that is, when the main line hand valve is closed, or when the piston bumps against the stop ring, the check valve closes, and effectively traps the pressure in the cylinder port. If the relief valve is set too high, and the adjuster for the relief valve is backed off to lower the pressure, the cylinder port gauge will not register the lower pressure, however, the pump port gauge will. To lower the cylinder pressure, the manual lowering hand valve must be opened slightly and then, if two gages are in place on the valve, both will follow the movement of the relief valve adjuster. When the cylinder is stopped, either by bumping against the stop ring or by the action of closing the main line hand valve, the flow through the check valve stops also, and the differential pressure across it drops to zero. Pump pressure and cylinder pressure are then effectively the same. EECO recommends that all pressure gauges be liquid filled and calibrated to 1000psi. One of the most important adjustments to set is the by-pass size adjustment. The by-pass piston must be open far enough to by-pass 100% of the pump output at minimum system pressure. This is done with the empty elevator at the lowest landing. Preset the UD adjuster to the open position by turning the adjuster screw out (CCW), and disconnect the UDS solenoid electrically. Put in an UP call and start turning the BP adjuster in (CW) until the car moves, then back it out until the car stalls, then back out 1/2 turn more and lock it. As in all hydraulic systems, cleanliness is important. EECO valves are equipped with fine mesh screens on the input adjusters, which should be inspected regularly. However, a clogged screen will manifest itself with deteriorating valve performance. For a comprehensive listing of possible valve troubleshooting, please visit EECO s websites at equipment.com or

5 Page 35 SAFETY AND SERVICING OF HYDRAULIC ELEVATORS by Roy W. Blain Constructional Safety For low-rise buildings, the elevator customer can choose between the hydraulic elevator with a machine room, usually in the basement of the building, or the electric (traction) elevator, increasingly without a machine room, with the machine drive in or directly adjacent to the hoistway and normally at the top of the building. In general, the hydraulic elevator has dominated the low-rise market because it is cheaper to build, install and service, and because it has a decidedly better safety record than the electric elevator. Especially in earthquake endangered areas, the hydraulic elevator has proven itself to be clearly the safer option. Due to the threat presented by swinging counterweights and also because the car is suspended from the top of the hoistway, the traction elevator is particularly vulnerable to a shaking building compared to the hydraulic elevator which is installed practically on the building s foundation. The July 2002 issue of EW informed us that the Seattle earthquake of February 2001 caused damage to what amounted to only 1% of the hydraulic elevators in the vicinity, compared to 11% of the electric elevators. Emergency Situations In the case of fire, rescue personnel have the advantage of working from the ground floor hydraulic machine room, rather than at the top floor or in the hoistway of an electric elevator where smoke and heat can prevent any Electric Elevator (Passenger trapped) Hydraulic Elevator (Passenger freed) Electric Drive Fire! Easy access to hydraulic drive and emergency lowering valve at ground floor level Earthquake Little or no damage to hydraulic drive. No counterweight to create extra danger Earthquake Rescue operation made precarious by damage to upper floor machinery & counterweight structure Hydraulic Drive attempt at rescuing someone trapped in the car. There is also the risk that with a counterweighted electric elevator, releasing the brake to lower the car may cause the car to go upward instead of down, possibly increasing danger to the passenger. a. Emergency power coil Ball valve d. 100% Duty coils b. Hand pump e. Self-closing manual lowering c. Slack rope valve 1-1/2 inches 2 inches EV 100 Safety Features of the EV 100 Valve A. An Emergency Power Coil (EN) enables the car to be lowered by push button in the car should the main electrical power fail. Optional. B. An integrated Handpump (HP) for manually raising the car during installation or in an emergency situation. Optional. C. A Slack Rope Valve (K), used with 1:2 roped hydraulics, prevents the ram from being manually lowered when the car is suspended by the safeties; otherwise slack ropes could become entangled with hoistway equipment. Required by EN81-2 Code. D. 100% Continuous-Duty Coils (M) ensure against coil burnout if they are energized for longer periods. Standard. E. The Manual Lowering Valve H, with a self-closing (dead man) function. Standard. Hydraulic elevator safety products independent of the control valve are: Pipe Rupture (overspeed) Valves mounted directly on the cylinder which are becoming standard worldwide. Hydraulic Microdrive, an auxiliary low-power raising and lowering unit, ideal for quiet, accurate releveling or slow-speed emergency movement of the car should the main power unit be out of operation. Educational Focus Compilation 35 Fire! Difficult or impossible access to electric drive & lowering device due to heat, smoke & elevation Considering the growing number of residential lifts being built, it is important that a member of the household can handle the procedure of manually lowering the car to the ground floor to release a stranded passenger in the event of an electrical power failure or other emergency. The safest such method is through the slow-speed, manual-lowering system of the hydraulic elevator, easily accessible at the ground floor and simple to operate.

6 Page 36 tion by briefly (three-to-five seconds) lifting and replacing the appropriate energized coil by hand, allowing several adjustment corrections to be made during one car travel between floors. R10 Rupture and Overspeed Valve MD Micro Drive Hydraulic Fine Positioning Preparation for Servicing Because the main drive, cylinder and control valve moving parts of hydraulic elevators all operate in oil, conditions for a long, trouble-free operating life are significantly increased. When it is reported that the elevator is defective, it often turns out that the presumed fault is simply a matter of an incorrectly adjusted valve. Friction, in the cylinder head or through misaligned guide rails, can be the reason for an uneven ride. Releveling of the car is not always due to leakage in the valve but can be the result of a hot system cooling down. For such reasons, before taking the control valve apart, double check the possible source of the problem and study the manufacturer s troubleshooting list. In the case of a Blain EV 100 valve, troubleshoot via the website: Once trial runs have been made, or a fault located, servicing begins with the positioning of the car. Unless circumstances dictate otherwise, sending the car between the two upper landings before switching off the electrical mains has the advantage of eliminating the possibility of the doors being left open at floor level during servicing. It also prepares the way for an initial down travel when servicing is completed, forcing air that may have entered through the valve out of the cylinder system and not into it, as is the case if the first operation following servicing were to be an up travel. Prior to opening up the main control valve, the cylinder line shut-off valve must be closed and the control valve exhausted of pressure by opening the manuallowering valve. The mains must remain switched off until the valve is completely re-assembled, otherwise an uninformed person in the building may at any time put in a call for the elevator. Also, through the hydraulic system cooling, the car may shift down and trigger the automatic releveling before the control valve is closed up. An oil shower would result. Solenoid Coils During servicing or adjustment of the EV 100 valve, instead of making a full floor to floor travel to check operation, time can be saved by removing the securing nuts on top of the coils and switching to deceleration or to accelera- 36 Educational Focus Compilation Manual switching of energized coils Once removed from the solenoid tube, an energized coil will begin to overheat after about 20 seconds. If necessary, to slow the rate of heating, place a millimeter (1/2-5/8 inch) diameter tool or short steel rod as core through the coil. Do not lay an energized coil to one side, it may overheat unnoticed. If the coil becomes too hot to hold, it must be replaced back over the solenoid tube and any further adjustment carried out with the elevator making normal floor-to-floor runs. Deceleration Switch, Distance Before Landing Often, not enough attention is paid to slowdown distances. The following chart will take the guesswork out of switch installation. Metric Imperial Elevator Speed Switch Elevator Speed Switch mps approx. cm fpm approx. inches

7 Page 37 Main Down Filter Up Pilot Filter Down Pilot Filter BLAIN EV 100 elevator valve Fine hair-like fibers in the oil stemming from cleaning rag, may on rare occasions settle on a sealing surface of a valve or solenoid seat causing a minor down leak and releveling of the car. The EV spare parts list shows the valve parts to check in the event of persistent releveling. Starting with solenoid D, cleaning the affected part or turning the solenoid seat over may be sufficient to cure the leak, otherwise its replacement will be necessary. It is not necessary to strive for perfect sealing in every valve in operation. Because code requirements assure a safe releveling system whether descent of the car of a few millimeters is caused by valve leakage or through the cooling of the oil in the cylinder pressure system, a minor leakage of the control valve can be tolerated. The European Code EN81-2 requires that the loaded elevator does not leak downward by more than 10 millimeters (3/8 inch) in 10 minutes. This is the standard used to determine if a valve must be serviced for leakage or not. Educational Focus Compilation 37 With no load in the car, the deceleration time should be seconds from full speed to leveling speed. The constant speed leveling time should be 1-2 seconds. Factors Affecting Accurate Landings If the leveling speed is fast, i.e., 0.1mps (20fpm), landing will not be as accurate as when the leveling speed is slower, i.e., 0.05mps (10fpm). A leveling speed between these values should be satisfactory. Following leveling, if the soft stop adjustment five is set too soft, stopping will be less accurate than when five is set for a quicker stop, seconds. A difference in landing accuracy between the elevator being loaded and unloaded can be due to the car underload leaning to one side by a few millimeters between the guide rails in the horizontal plane causing an alteration in the operating of the stop switch by some centimeters in the vertical plane. Particularly when the mechanic cannot directly see the operation of the elevator car, it is possible that the elevator has not finished deceleration from fast speed before reaching the floor. In other words, the elevator has not slowed down to its correct leveling speed before the stop switch is actuated. In the machine room, the turbulant noise within the valve during leveling can be heard and should last 1-2 seconds, following seconds deceleration time (no load in the car). Car Not Visible from Machine Room If the car cannot be seen during adjustment of the valve, the acceleration and deceleration times can be heard in the machine room from the change in sound of the oil flow in the control valve as the speed of the car changes. With no load in the car, the duration of the speed changes should be as follows: Up acceleration, adjustment 2, 2-3 seconds Up decelaration, adjustment 3, 2-3 seconds Up leveling time adjustment 4, 1-2 seconds Down accelerate adjustment 6, 2-3 seconds Down decelerate, adjustment 8, 2-3 seconds Down leveling time, adjustment 9, 1-2 seconds Oil Filtration and Leakage In the case of the Blain EV 100 elevator control valve, it is not necessary to install an extra filter into the powerunit system. Sensitive sections of the EV 100 are protected against foreign substances by three built-in, self-cleaning filters: one in the cylinder main pressure line, one in the cylinder pilot pressure line and one in the pump pilot pressure line. Clogging of the filters in EV valves is prevented by the filters being positioned in flow turbulent sections of the valve so that contamination cannot settle on the filter s surface. Inspection of these filters need not be more frequent than one time per year.

8 For practical reasons, a quicker method for judging valve leakage is to close the ball valve in the cylinder line and observe the gauge showing pressure in the cylinder chamber of the valve. If this pressure falls to zero in less than 20 seconds, it may be necessary to service the valve, depending on the diameter of the main ram and the sensitivity of the customer. Overheating of the Oil Oil temperatures above 55 C (130 F) should be avoided, otherwise the efficiency of the pump drops considerably, and its life is reduced. Aging of the oil is accelerated as well. Overheated oil also results in frequent releveling. Causes of overheating are: Up leveling being too long due to the leveling speed being slower than necessary or the slow down switch being set too low. Machine room ventilation inadequate. The frequency of operation is too high for the rate of heat dissipation from the installation. As a temporary measure to avoid overheating of the oil which would otherwise result in the automatic shut down of the elevator, the down speed can be slowed to reduce the frequency of operation, until a permanent solution is installed. If the degree of overheating is not excessive, and it takes, for example, two to three hours for the oil temperature to rise from C ( F), it may be sufficient to improve air circulation around the power unit, for example through the installation of a kW ventilator extracting air out of the machine room or through a fan of similar power, blowing air over the tank, or both. Coolers are (rarely) necessary in hydraulic elevators. If extensive overheating nevertheless does occur through continuous operation of the elevator, the following measure can be taken. Depending on the size of the elevator, it will be necessary to install a (between 10 and 50 lpm. [3-13gpm] pump) to circulate the hot oil through a fan cooled radiator of about fan kw. It remains essential that there is sufficient extraction of warm air out of the machine room or that the cooler is outside of the machine room, for example in the elevator hoistway. The effective cooling power of a cooler need not be more than onefourth of the main elevator motor drive and should not be confused with the power of its fan drive which normally need only be 0.1 or 0.2kW. The cooling system should automatically switch into operation when the oil reaches C (85-95 F). Below these temperatures, the small temperature difference between the air which cools and the warm oil may find the cooler running continually with little effect. 38 Educational Focus Compilation Blain Explosion-Proof Elevator Valves MEX-EV The latest safety product to be added to the Blain Hydraulics control valve program is the explosion-proof solenoid MEX 24VDC, which has been successfully tested and approved by the internationally recognized German Physical and Technical State Institution in Braunschweig, Germany. The MEX solenoid can be installed wherever the standard Blain solenoid M is employed for its control valves. The construction and performance of the MEX corresponds to the European standards. CENELEC DIN EN and DIN EN Ambient temperature -20 C to 60 C Ex II2G EEx m II T4 Enamelled wire insulting class H Housing protection class IP 68 Electrical apparatus for potentially explosive atmosphere Encapsulation m. Voltage 24 V DC Current 1.2 amps Certificate-no. PTB 02 ATEX 2193 X EV-MEX explosion-proof solenoid Spare Parts Traveling to the site and searching for the cause of a problem can be expensive. Having to repeat the journey because a simple replacement part is not on hand can usually be avoided if a complete valve is kept along with the service kit in the truck. If during servicing, a flange, adjustment, securing bolt or other part is damaged or misplaced, a spare valve in the truck can be a blessing, since it includes all parts. It may also be used for a complete renewal, should it be necessary, provided that any so-called borrowed parts have been faithfully replaced. A full set of up-and-down flow guide sizes, a seal kit, two spare solenoid coils, a set of springs and the troubleshooting list, should take care of any remaining eventuality. If a problem could not be solved, call the valve supplier before leaving the site. His experience can often save an extra journey. Roy W. Blain, an HNC mechanical engineer from Salford Tech in the U.K., has spent two years developing hydraulic extrusion presses in Bournemouth. He worked for five years on synchronized heavy lifting gear at Von Roll in Switzerland and six months at True Trace in El Monte, California on hydraulic copying valves before joining Elevator Equipment Co. Since 1970, Blain has built up an elevator valve company close to Stuttgart, Germany which exports over 80% of its products.