The drop in the residual pressure in the vacuum system below the permissible values when the pump PN 40 is operating indicates a critical leakage or wear of working pairs. Unlike the oil analogues, dry-vacuum in piston units of this type requires accurate calibration of gaps and the ideal state of seals, since the absence of a liquid shutter makes the mechanism sensitive to the slightest leaks. Failure to comply with the pumping-out time standards for the tank volume usually indicates the need for immediate inspection of the valve group or replacement of the piston rings.
Operational diagnosis begins with the analysis of the vacuum meter readings with a silenced inlet pipe. If the arrow of the device does not reach the zone -0.6 ...-0.8 kgf/cm2 during the first minutes of idling, this is a direct signal about the presence of air suction or mechanical malfunction of the internal nodes. Ignoring these symptoms leads to the impossibility of taking fluid and downtime of special equipment.
Principle of operation and features of dry vacuuming
Pump PN 40 belongs to the class of piston vacuum pumps, where the creation of the vacuum occurs due to the reciprocal movement of the piston in the cylinder. The design of the “dry” type implies work without a permanent oil shutter in the working chamber, which excludes the ingress of oil refining products into the pumped environment, but imposes strict requirements for the quality of surface treatment. Tightness in such systems is provided by a tight fit of valves and the elasticity of special cuff seals.
The key difference from oil systems is the lack of the effect of sealing gaps with an oil film. Therefore, even microscopic scratches on the cylinder mirror or wear of the rings lead to gas leaks from the injection zone to the suction zone. This phenomenon directly reduces efficiency It does not allow to achieve the design values of the vacuum.
It is important to understand that the term “dry” does not mean the complete absence of lubrication in the mechanism. The friction of the piston group is compensated by periodic lubrication or the use of low friction materials, but there should not be an excess amount of oil in the working volume that could be emulsified with the vapors being pumped.
⚠️ Note: Operation of the pump PN 40 with signs of a strong air sucking through the glands can lead to overheating of the piston group due to a violation of the heat sink and operation in a constant maximum load mode.
Productivity standards
For an objective assessment of the technical condition of the equipment, it is necessary to rely on passport data and industry standards. Pump PN 40 It must provide a certain air pumping rate and reach the maximum residual pressure in a regulated time. Deviation from these parameters by more than 10-15% is considered a sign of malfunction.
The main controlled parameters are the vacuum time in the tank of 6000 litres and the maximum inlet dilution. In the working condition of the unit, the pumping time should not exceed the established limits, and the vacuum arrow should confidently enter the working green zone of the scale.
Below is a table with indicative technical characteristics that should be guided when accepting equipment or conducting routine diagnostics:
| Parameter | Unit of measurement | Normative value | Permissible deviation |
|---|---|---|---|
| Residual pressure limit | kgs/cm2 (at) | not more than 0.25 | ±0,05 |
| Pumping time (tank 6m3) | minute | 15-18 minutes | temperature-dependent |
| Shaft speed | min | 700-900 | ±50 |
| Productivity | m3/min | 2,5 - 3,0 | at least 2.2 |
It should be borne in mind that the actual figures can vary depending on atmospheric pressure, ambient temperature and humidity. Cold air has a higher density, which may slightly increase the time of vacuum creation, but the maximum pressure must remain stable.
Step-by-step instructions for checking the vacuum system
Diagnosis begins with visual inspection and equipment preparation. Make sure the pump is heated to operating temperature, as the cold gaps can be increased and the lubricant can have high viscosity. Disconnect the suction hose from the tank or securely shut off the inlet pipe to check the tightness of the pump itself.
Start the engine and let it go to working speeds. Turn on the pump drive and watch the vacuum meter readings. If the dilution is created slowly, consistently check the nodes from the output pipe to the input one using the exclusion method.
For accurate localization of the leak, use the following algorithm of actions:
- 🔍 Check the tightening of all flange bolt joints and the presence of visible damage to the hoses.
- 👂 Listen to the characteristic whistle on hearing, which emits the place of air sucking under vacuum.
- 🧴 Pour a soap solution on suspicious joints - the appearance of bubbles will indicate leakiness.
- 🌡️ Control the temperature of the pump body: local overheating may indicate dry friction due to lack of lubrication.
☑️ Checklist of primary diagnosis of PN 40
Pay special attention to the condition of the return valves. Sticking or loose closure of the plate of the valve leads to a reverse air injection into the system during the compression stroke, which negates all the work of the piston. Disassembly and defective valve group often solves the problem of low vacuum.
⚠️ Warning: When conducting a soap solution blowing test, avoid getting a large amount of moisture into the electric part of the drive or on the hot surfaces of the exhaust system.
Typical malfunctions and methods of their elimination
The most common cause of productivity loss is wear and tear. piston-ring. In conditions of "dry" friction, they wear out faster than in an oil bath, lose elasticity and cease to fit tightly to the walls of the cylinder. This causes a gas breakthrough and a drop in compression. The solution to the problem is to replace the rings and, if necessary, swell the cylinder for the repair size.
The second most common problem is damage. valve-plate. Cracks, chips or deformation of the edges do not allow the valve to tightly close the hole. As a result, the environment is flowing back. Defective plates are not subject to repair and require mandatory replacement with new original parts.
Nuances of seal replacements
When replacing cuff seals, be sure to lubricate them with a working environment or a special lubricant before installation. Dry installation can lead to a bully edge at the first stroke of work, which will instantly put a new part out of order.
Do not forget about the integrity of the gaskets under the cylinder head and flanges. Overheating or improper tightening of bolts leads to their penetration. In this case, the air is sucked directly into the working chamber, bypassing the inlet tract. Replacement of gaskets should be made by a set with observance of the moment of tightening.
If the pump is equipped with a cylinder lubrication system, check its operability. Clogging of wicks or channels of supply of lubrication leads to work "on dry", which causes the jack of the cylinder mirror and jamming of the piston.
Impact of maintenance on the resource
Regular maintenance is the key to the stable operation of the vacuum system. Timely change of oil in the gearbox (drive) prevents wear of gears and bearings that transfer movement to the crank-shaking mechanism. Dirty oil or its deficiency leads to backlashes that disrupt the geometry of the piston’s motion.
The cleanliness of the intake air also plays a role. If abrasive particles enter the pump through the inlet pipe, they act as a polished abrasive, accelerating cylinder wear. Installation of high-quality filters at the entrance significantly prolongs the repair period.
- 🛢️ Control the level and condition of lubricants according to the lubricant map.
- 🔧 Regularly tighten fasteners that are subject to vibration.
- ❄️ In winter, avoid water entering the system to avoid freezing and breaking down parts.
The main resource of the PN 40 depends on the purity of the working environment and the presence of lubricant in rubbing pairs, even in "dry" modifications.
Ignoring routine work leads to the accumulation of defects. For example, a small backlash in a rod eventually destroys the bearing, which causes the piston to beat and the cylinder to wear rapidly. An integrated approach to maintenance avoids expensive overhauls.
Frequently Asked Questions (FAQ)
Why does the PH 40 pump hum, but does not create a vacuum?
The hum in the absence of vacuum most often indicates the turning of the veneer on the shaft or the breakage of the rod inside the crankcase. It is also possible to destroy the piston group when the piston dangles in the cylinder without creating a compression. Disassembly and defective mechanical part is required.
Can I use oil to lubricate the cylinders of the PN 40?
The use of oil is permissible only if the pump design provides for a system of lubrication of cylinders (fitting or drip). For dry pumps with Teflon or graphite rings, adding oil may not be desirable, as it mixes with the pumped medium. Read the product's passport.
What is the permissible temperature of the pump body when working?
The normal operating temperature of the cylinder body is considered to be a range of up to 80-90 ° C. Exceeding 100 ° C indicates insufficient lubrication, too high revolutions or violation of thermal gaps. Short-term heating is permissible, but prolonged work during overheating leads to jamming.
How often should I change the rings?
The resource of the rings depends on the intensity of operation and quality of service, but on average it is 500-800 hours. If there are signs of a drop in performance, not eliminated by valve adjustment, the rings should be replaced.