TECHNICAL INFORMATION

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Josephine Snow
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1 DEFINITION OF For pressure we mean the ratio between a force exerted by a fluid on the surface on which it acts; it is dimensionally expressed in force units per surface units. There are a lot of pressure units, the most used are: BAR (0 5 Pa), Pascal (N/m ), ATE (Kg/cm ), TORR (mm HG)and for Anglo-Saxon countries PSI (pound/square inch). UNITS bar Pa Mpa , ATE (Kg/cm ) TORR (mm Hg) PSI bar Pa Mpa ATE (Kg/cm ) TORR (mm Hg) PSI 0 5 0,, ,0x0-5 7,5x0-0,45x0 -,x0 -,,x0-4,6x ,98 9,8x0 4 9,8x0-76 4,,94x0-6,895x ,895x0-7,0x0-5,7 Concerning pressure, the most commonly used terms for the utilisation of pneumatic components are as follows. - ATMOSPHERIC : it is the pressure exerted by the air on bodies. More precisely it is the pressure exerted on a surface of cm referred to an height of 0 ( zero ) meters above the sea level with a temperature of 0 C and 65% of humidity that is equivalent to a 0, m column of H O or a column of 760 mm of Hg. - RELATIVE : it is the pressure exerted by a fluid on the inner surfaces of its container. It is usually read on the pressure gauge. - ABSOLUTE : it is the pressure of a fluid respect to the absolute vacuum. It is obtainable adding the relative pressure to the atmospheric one. ex. Reading on pressure gauge relative pressure 5 BAR Absolute pressure 6 BAR - UPSTREAM : pressure of the compressed air at the inlet of the pneumatic component. - DOWNSTREAM : pressure of the compressed air at the outlet of the pneumatic component. - DIFFERENTIAL P: it is the difference between upstream and downstream pressure. The main laws of physics concerning pressure that are useful for the correct use and sizing of the pneumatic components are as follows. - BOYLE-MARIOTTE S LAW: the volume of a closed quantity of perfect gas contained at a constant temperature (isothermal) is inversely proportional to the pressure. That means that the product between the volume and the pressure is constant. T constant PV constant we deduce P V P V constant - GAY-LUSSAC S LAW: the volume of a gas contained at a constant pressure (isobar) is directly proportional to the absolute temperature. if P constant V /V T /T With constant volume, the pressure is directly proportional to the temperature if V constant P /P T /T - GENERAL EQUATION of GASES: it is the general law that sum up the two above mentioned laws. It runs a transformation of three variables: given two parameters able to individuate the thermodynamic condition, it enables us to individualise the third one. PV n RT where: P pressure V volume R universal perfect gas constant (9,7 N m / K) T absolute temperature in Kelvin (7 K 0 C) n gram molecules of gas contained in the volume 4,5 we deduce P V / T P V / T R costant

2 TEMPERATURE As you can see in the main laws of physics, mentioned in the previous page, the temperature influences the pressure and so it is an element that directly influences the pneumatic circuits. The most used temperature measure units are : KELVIN (K), CELSIUS ( C ) and FAHRENHEIT ( F). The correspondences between the various measure units, are as follows : CELSIUS KELVIN + 7,5 CELSIUS (FAHRENHEIT - ) x 5/9 FAHRENHEIT (9/5 x CELSIUS) + KELVIN CELSIUS - 7,5 For more convenience look at the below mentioned table KELVIN (K) CELSIUS ( C) FAHRENHEIT ( F) In the planning of pneumatic circuits, we use measure units concerning air volumes in normal conditions. The NORMAL liter of air (Nl) is the most commonly used measure unit, that corresponds to dm of air at a temperature of 0ºC (+7ºK) and to a pressure of Kg/cm (atm), that is the normal pressure of the air at the sea level. In the meantime we use the NORMAL cubic meter (Nm ) that corresponds to 000 Nl. FLOW RATE DETERMINATION To establish if a valve has got the sufficient flow rate for a specific purview, we use certain below mentioned parameters, that consider some indispensable elements for their determination. These elements that are to be known are: a) supply (upstream pressure); c) loss of pressure (differential pressure); b) outlet (downstream pressure); d) working temperature;. - FLOW RATE FACTOR kv It is the quantity of water, expressed in dm /min (liter/minute). that passes through the valve with a differential pressure of BAR at the temperature of 0º C. - FLOW RATE FACTOR KV As above mentioned, but expressed in m /h (cubic metre/ hour) - FLOW RATE FACTOR CV As above mentioned, but following the Anglo-Saxon measure unit, that is the quantity of water expressed in US gallons / minute (US gallon,785 dm ) with a differential pressure of PSI (0,07 BAR) at the temperature of 60ºF (5,6ºC). - EQUIVALENT SECTION S The value S, expressed in mm represents for a valve the theoretic hole of flow passage. Every model of YPC valve shows always this value CONVERSION TABLE BETWEEN THE FLOW RATE FACTORS Unità S (mm ) kv (dm /m) S (mm ) KV (m /h) 0,979 6,667,66 Cv (US-Gal.) 8 kv (dm /m),59 KV (m /h) 4, 0,858 Cv (US-Gal.) 0,794 0,048 0,055 0,06 0,07 NOMINAL FLOW RATE ( Qn ) The nominal flow rate Qn that is generally expressed in Nl/m, is an approximate guide of the flow rate of the air (Nl) that passes through the valve in an unit measure of time (minute) with an upstream supply pressure (P ) of 6 BAR and a differential pressure ( P P -P ) of BAR, corresponding to a downstream outlet pressure (P ) of 5 BAR at the temperature of +0ºC. The nominal flow rate is an approximation because it's value can change depending on the type of construction of every component, but it is an acceptable value. The under mentioned easy formula determinates the nominal flow rate (Qn), knowing the equivalent section S (mm ): Qn 54 x S An example for YPC valves is : - SF0-00C solenoid valve 5/ single acting /8 S,6 mm Qn 54 x,6 ~ 680 Nl

3 PROTECTION CLASS FOR COILS WITH CONNECTOR For protection class, we mean the intrinsic power of a live electrical equipment to protect itself and everything against casual contacts and the penetration of solid particles and water. It is defined with the abbreviation I.P. followed by figures: the first one from 0 to 6, defines the protection against casual contacts and the penetration of dust; the second one from 0 to 8, defines the protection against water. The below tables describe the various degrees of protection. PROTECTION CLASS AGAINST CASUAL CONTACTS AND PENETRATION OF FOREIGN PARTICLES First Protection figure Denomination Explanation No special protection for people against casual contacts with live or moving parts. No 0 No protection. protection of the equipment against the penetration of foreign solid particles. penetration of large sized solid particles. Protection against casual contacts of large surfaces with live or moving parts inside the equipment, for example contacts with hands, but no protection against voluntary access to these parts. Protection of the equipment against the penetration of solid particles with a diameter larger than 50 mm. penetration of medium -sized solid particles. Protection against contacts of fingers with live or moving parts inside the equipment. penetration of solid particles with a diameter larger than mm, such as fingers. penetration of small-sized solid particles. Protection against contacts of tools, wires or similar, ticker than.5 mm with live or moving parts inside the equipment. penetration of solid particles with a diameter larger than.5 mm, such as tools and wires. 4 penetration of very smallsized solid particles. Protection against contacts of tools, wires or similar, thicker than mm with live or moving parts inside the equipment. penetration of solid particles with a diameter larger than mm, such as tools and wires. 5 Protection against dust deposits. Full protection against contacts with means of any kind with live or moving parts inside the equipment. Protection against dust deposits. The penetration of dust is not completely eliminated, but it is reduced in order to assure the good working of the equipment. 6 Protection against dust penetration. Full protection against contacts with any kind of means with live or moving parts inside the equipment. Full protection against the penetration of dust. Second Figure PROTECTION CLASS AGAINST DUST PENETRATION Protection Denomination Explanation No protection. drops falling perpendicularly. drops falling slantwise. dripping. sprays. jets. Protection against flood. Protection against immersion. Protection against submersion. No special protection. Water drops that fall perpendicularly must no cause any harmful effect. Water drops that fall slantwise up to 5º with respect to the vertical, must not cause any harmful effect. Water that falls slantwise up to 60º with respect to the vertical, must not cause any harmful effect. Water sprayed against the equipment from any direction must not cause any harmful effect. Water jets flung against the equipment from any direction must not cause any harmful effect. he water penetrating into the equipment due to a temporary flood, for example during rough sea conditions, must not cause any harmful effect. Should the equipment be immersed for a pre-established time and at a pre-defined pressure, the water must not penetrate in such a quantity as to damage the equipment. Should the equipment be submerged at a pre-defined pressure and for an undetermined period of time, the water must not penetrate in such a quantity as to damage the equipment.

4 PNEUMATIC SYMBOLS The need to uniform the graphic units in the various countries has lead the national ruler organism (UNI VDMA UNITOP etc.) and international ruler organisms (CETOP ISO etc.) to give common symbols to the various pneumatic components that are in a circuit. We hereby give a main table of the commonest symbols used in pneumatic schemes. DIRECTIONAL CONTROL VALVES Two-way valves - position - normally closed Two-way valves - position - normally open Three-way valves - position - normally closed Three-way valves - position - normally open Four-way valves - position - common exhaust connection Four-way valves - position - common exhaust connection normally closed centre. Five-way valves - position - separate exhaust connection Five-way valves - position - normally opened centre Five-way valves - position - normally closed centre Five-way valves - position - centre with pressure CONNECTIONS The connections drawn in the symbol, must correspond to the connections of the elements. The key of reading is made of numbers ( ISO CETOP standard symbols ) or letters ( symbols used in the Far East ) which combination makes possible the definition of the connections and their function. In our synthetic technical information, we consider only the definition and the significance of the connections given in figures ( ISO / CETOP standard symbols). We provide only a comparison table between figures and letters. Connections are divided into two categories: a ) main connections b) command connections -a) mains connections They are identified by only one number, more precisely: supply connection and 4 and 5 utilisation connection with only one exhaust connection utilisation connection with two exhaust connections air exhaust connection with only one exhaust connection air exhaust connection with two exhaust connections In a 5/ or 5/ valve the utilisation () communicates with the exhaust () and the utilisation (4) communicates with the exhaust (5). - b) command connections They are identified by two figures ( 0 ) ( ) ( 4 ). (0) means: pressure connection closed if the command connection is not under signal. 0 0 () means: utilisation connection joined to the connection if the command connection is under signal (4) means: connection joined to the connection 4 if the command connection 4 is under signal 4 4 5

5 COMPARATIVE TABLE CONNECTIONS BETWEEN FIGURES ( ISO CETOP ) AND LETTERS ( FAR EAST ) SUPPLY UTILISATION () - (P) () - (B) (0) - (Y) () - (Z) for or way valves EXHAUST UTILISATION () - (S) (4) - (A) () - (Y) (4) - (Z) for 4 or 5 way valves EXHAUST (5) - (R) CONTROLS GENERIC BY STEM OR KEY MANUAL BY PUSH-BUTTON BY LEVER MECHANICAL BY SPRING BY ROLLER LEVER BY PEDAL BY UNIDIRECTIONAL ROLLER LEVER PNEUMATIC DIRECT ACTION OF INDIRECT ACTION OF COMBINED BY SOLENOID WITH ONE PILOT VALVE BY SOLENOID ONE PILOT ASSISTED ELECTRIC OPERATED VALVES BY SOLENOID WITH ONE WINDING BY AIR+ MECHANICAL SPRING RETURN COMPLEMENTARY VALVES FIXED FLOW REGULATOR SHUTTLE VALVE (OR type) BI-DIRECTIONAL FLOW REGULATOR SILENCER UNI-DIRECTIONAL FLOW REGULATOR NON-RETURN VALVE WITHOUT SPRING QUICK EXHAUST VALVE NON-RETURN VALVE WITH SPRING PIPES AND CONNECTION LENE ELETTRIC LINE CONTROL LINE LINE CONNECTION EXHAUST LINE CROSSOVER FLEXIBLE LINE PNEUMATIC SOURCE

6 AIR TREATMENT EQUIPMENT AIR FILTER WITH MANUAL CONDENSATE SEPARATOR FILTER WITH CONDENSATE SEPARATOR REDUCER WITH GAUGE WITHOUT EXHAUST VALVE (NOT RELIEVING) CON VALVOLA DI SCARICO (RELIEVING) WITH AUTOMATIC FILTER - REDUCER GROUP WITH MANUAL FILTER - REDUCER - LUBRIFICATOR GROUP WITH AUTOMATIC device converting an PNEUMOELECTRIC imput pneumatic signal into an output electrical TRASDUCER signal SWITCH LUBRIFICATOR device switching at an adjustable fixed pressure CYLINDERS AND ACTUATORS DOUBLE ACTING CYLINDER THROUGH ROD COMPRESSOR ROTARY ACTAUTOR OPPOSED FRONT SPRING TANDEM CYLINDER DOUBLE PUSH SINGLE ACTING CYLINDER REAR SPRING DOUBLE ACTING CYLINDER DOUBLE STROKE CONVOLUTED AIR SPRING ROD AND PISTON UNIT TYPE ROD AND PISTON UNIT WITH MAGNETIC PISTON AND ADJUSTABLE CUSHIONING AT ONE END WITH ADJUSTABLE CUSHIONING AT ONE END WITH MAGNETIC PISTON AND ADJUSTABLE CUSHIONING AT BOTH ENDS WITH ADJUSTABLE CUSHIONING AT BOTH ENDS WITH NOT ROTATING PISTON DEVICE WITH MAGNETIC PISTON NOT ADJUSTABLE WITH PISTON ROD LOCKING UNIT

7 NOTE PANTHER

Introduction to Pneumatics

Introduction to Pneumatics Pneumatics Symbols Air generation and distribution Table 1: Symbols use in energy conversion and preparation ITEM SYMBOL MEANING Compressor SUPPLY Pressure Source Pneumatic Pressure