CNC Lubrication Pump Selection Guide: Technical Specifications & Applications

The selection of an appropriate CNC lubrication pump for CNC machine applications requires careful consideration of technical specifications, system compatibility, and operational requirements. Inadequate lubrication systems can contribute to premature component wear, reduced machining accuracy, and increased maintenance costs.

This technical guide provides comprehensive specifications and selection criteria for CNC lubrication pump systems, covering reservoir sizing, voltage requirements, lubricant compatibility, and system integration considerations.

Table of Contents

1. Technical Overview
2. Lubrication Pump Classification
3. System Requirements Analysis
4. Pump Selection Criteria
5. Technical Specifications
6. Manufacturer Comparison
7. Installation and Maintenance Protocols
8. Technical FAQ
9. People Also Ask
10. Engineering Recommendations
11. Technical Resources

Closing note: Selecting a lubrication pump based on reservoir size requires evaluating flow rates, viscosity levels, and operating pressures. Choosing an appropriate pump from manufacturers such as Bijur Delimon or SKF supports reliable CNC machinery performance and lower maintenance costs over time.

1. Introduction

Importance of Lubrication in CNC Machines

CNC machine lubrication is essential to precision manufacturing. Without proper lubrication, advanced CNC machinery may experience:

• Premature wear of critical components
• Reduced accuracy affecting part quality
• Increased downtime and maintenance costs
• Shortened machine lifespan

Role of Lubrication Pumps in CNC Performance

A CNC lubrication pump is central to the lubrication system, ensuring:

• Consistent lubricant delivery to critical points
• Automated operation reducing manual intervention
• Precise lubricant metering preventing waste
• System monitoring and fault detection

Field reports indicate that consistent CNC machine lubrication can contribute to longer component life and fewer unplanned shutdowns compared with inadequately lubricated equipment.

Manufacturer performance data indicates that effective automatic lubrication systems can reduce maintenance costs and improve uptime, with reported payback periods in the 6–18 month range.

Guide Overview

This guide provides selection guidance for machine operators, maintenance managers, and purchasing decision-makers to choose an appropriate lubrication pump based on machine requirements, operational conditions, and budget constraints.

2. Lubrication Pump Classification

Manual vs Automatic vs Centralized Systems

Understanding the classification of CNC lubrication pump applications requires systematic evaluation of operational requirements and system complexity.

For comprehensive information on different types of lubrication systems, including detailed comparisons of single-line, dual-line, and progressive configurations, technical specifications and application guidelines are available.

Implementation Example

Illustrative Example: Automotive Parts Manufacturer

The following illustrative example reflects reported results from a mid-size automotive parts manufacturer that upgraded from manual lubrication to a 3L automatic electric pump system across 12 CNC machining centers:

Reported baseline:

• Manual lubrication every 8 hours
• 2-3 unplanned shutdowns per month
• Annual bearing replacement costs: $18,000
• Maintenance labor: 4 hours/day

Reported after 12 months:

• Zero lubrication-related shutdowns
• Bearing replacement costs: $6,000 (67% reduction)
• Maintenance labor: 30 minutes/day (87% reduction)
• Total savings: $45,000 annually
• System payback period: 8 months

The reported outcome was fewer unexpected failures and reduced time spent on manual lubrication tasks.

5. Key Factors to Consider When Selecting a Lubrication Pump

Machine Size and Complexity

Small CNC Machines (Desktop/Benchtop)

Recommended: 0.5L-1L manual or small electric pumps

• Limited lubrication points (2-6)
• Lower pressure requirements
• Budget-conscious solutions

Medium CNC Machines (Production)

Recommended: 2L-4L automatic electric pumps

• Multiple lubrication points (6-20)
• Automated operation required
• Common configuration for mid-size production CNC machines

Large CNC Machines (Industrial)

Recommended: 4L+ centralized systems

• Extensive lubrication points (20+)
• Complex distribution networks
• Maximum reliability requirements

4. Pump Selection Criteria

Reservoir Capacity Specifications

Reservoir sizing directly impacts maintenance intervals and operational continuity. The following specifications provide guidance for capacity selection based on machine requirements:

0.5L Reservoir Systems

Technical specifications:

• Service interval: 1-2 weeks
• Lubrication points: 2-4
• Operating pressure: 1.5 MPa
• Outlet configuration: M8 or M10 threads
• Cost specification: $25

1L Reservoir Systems

Application parameters:

• Target machines: Medium CNC lathes, small machining centers
• Service interval: 2-4 weeks
• Lubrication points: 4-8
• Cost specification: $50-$75

2L Reservoir Systems

System capabilities:

• Target applications: Standard machining centers, production lathes
• Service interval: 1-2 months
• Lubrication points: 8-15
• Cost specification: $150-$200

3L Reservoir Systems

Operational specifications:

• Production environment compatibility
• Service interval: 1-2 months
• Lubrication points: 8-15
• Cost specification: $150-$200

4L Reservoir Systems

Heavy-duty specifications:

• Large machining centers, multi-axis machines
• Service interval: 2-3 months
• Lubrication points: 15+
• Cost specification: $150-$200

6L Reservoir Systems

Continuous operation specifications:

• Heavy-duty continuous operation requirements
• Service interval: 2-3 months
• Lubrication points: 15+
• Cost specification: $200-$300

Engineering consideration: Smaller machines with infrequent lubrication requirements may utilize simpler, cost-effective pump configurations. Selection depends on operational duty cycle and equipment utilization rates.

Technical demonstrations: Product Demo 1 | Product Demo 2 | Product Demo 3

Electrical System Integration Requirements

DC24V Configuration – Recommended Standard

Technical advantages for CNC applications:

SKF MKF2 Oil Lubrication Pump – Industry standard for oil applications

SKF P203 Grease Lubrication Pump – Grease pumping applications

Power specifications:

• Oil pump systems: Maximum 20W power consumption
• Grease pump systems: Maximum 60W power consumption
• SELV (Safety Extra Low Voltage) compliance
• Universal CNC control system compatibility

Engineering rationale: DC24V voltage provides optimal safety margins for operator interaction while delivering sufficient power for most CNC lubrication pump applications. Safety considerations favor low-voltage systems in manufacturing environments.

AC220V/230V Configuration – High Performance Applications

Application requirements: Systems requiring higher pressure or increased discharge rates beyond DC24V capabilities.

Technical analysis: DC voltage limitations become apparent when applications require elevated power for high-pressure or high-discharge requirements. Most CNC lubrication pump systems maintain compact dimensions while requiring significant power output. AC220V configuration enables compact form factor with enhanced power delivery capabilities (Power = Pressure × Volume).

0.5L lubrication pump configuration

3L oil mist system configuration

1L PDI Grease Pump configuration

AC380V/440V Configuration – Industrial Applications

High-power system requirements: Applications utilizing trochoid pump technology with power requirements reaching 120W necessitate three-phase motor configurations.

Design consideration: CNC machinery design requires careful evaluation of power requirements. Insufficient or excessive power specifications can negatively impact system performance. Proper voltage pump system selection ensures optimal operational parameters.

Lubricant Compatibility Analysis

Oil-Based Lubrication Systems

Technical applications:

• Linear guide systems and ball bearing assemblies
• Rotating components and standard bearing applications
• High-speed operational requirements
• General CNC operational parameters

Application analysis: Standard CNC machinery utilizes oil lubricants for components including linear guides, ball bearings, and rotating assemblies due to superior flow characteristics and heat dissipation properties.

Grease-Based Lubrication Systems

Specialized applications:

• Press machinery installations
• Textile machinery (oil migration restrictions)
• High-load, low-speed component applications
• Contamination-resistant requirements

Engineering constraint: Press machinery and textile applications prohibit oil migration due to contamination requirements. Grease-based lubrication systems provide controlled lubricant placement for these operational constraints.

For detailed specifications on grease pump systems and lubrication grease pump configurations, including pneumatic, electric, and progressive pump options with NLGI grade compatibility from #000 to #3.

Technical conclusion: CNC lubrication pump selection based on appropriate lubricating agent specifications directly impacts operational longevity, component durability, and performance optimization throughout operational cycles.

5. Technical Specifications

CNC Machine Classification Requirements

CNC machinery varies significantly in lubrication system requirements. Machine type and configuration determine appropriate pump specifications and system architecture.

CNC Lathe Specifications

Technical requirements: CNC lathes and standard machining centers require gear pump configurations delivering constant flow rates. Component design exhibits reduced susceptibility to friction-induced stress.

Recommended systems:

• SLR (Simple Line Resistance) configurations
• Constant flow rate delivery mechanisms
• Manual or electric operation options

CNC Machining Center Specifications

Multi-axis considerations: Multi-axis machinery requires progressive lubrication systems ensuring equal lubricant distribution across all axes. This configuration ensures operational continuity and reduces component wear patterns.

Technical requirements:

• Electronic controller pump configurations
• Variable delivery rate capabilities
• PDI system integration for precision applications

Multi-Axis Machine Requirements

Electronic control integration: Electronic controller pump configurations enable variable delivery rate adjustment for material volume variations during machining operations.

Engineering assessment: Proper CNC lubrication pump selection based on specific machinery requirements requires systematic evaluation but provides optimal performance and operational durability. Technical consultation regarding CNC machine lubrication pump applications should precede procurement decisions.

Cyclic Piston Pump Specifications: Timed Automatic vs Manual One-Shot

CNC pumps look similar on the outside; the specifications below separate them. Representative values from two widely used configurations:

Three details matter beyond the headline numbers. Repeatability: the spring-discharge mechanism holds ±3% volume repeatability and ±2% pressure consistency despite ±10% voltage fluctuation, because discharge energy comes from a calibrated spring, not the motor. Filtration: a 40-micron inlet filter is standard, 25-micron recommended, since meter-unit orifices clog easily. Low-level switch: a reed-switch float triggers at roughly 500 ml remaining, giving the control an “OK to run” or “low oil fault” signal.

IsoHiTech stocks machine-tool lubrication pumps and complete retrofit kits in these classes. The Bijur-compatible #34819 TM-5 electric lubrication pump provides timed 3.2 cc discharge with a 3 L reservoir and pre-wired connector for machining-center retrofits. For manual mills, the Bridgeport 1-Shot lubricator kit converts grease zerks to a 9-point SLR oil system with everything included. Browse the Bijur lubrication pump category and the automatic oil lubrication pump category for the full range.

SLR vs. PDI: Choosing the Metering Method

The pump is only half the decision — the metering method determines dosing accuracy:

The practical difference shows up at unbalanced points: a vertical Z-axis guideway with high back-pressure receives significantly less oil than an open X-axis in an SLR network, while a PDI injector forces its exact dose regardless of back-pressure. For general-purpose machines, SLR with a quality cyclic pump is acceptable and economical; for precision or unattended machining, PDI’s per-point visual confirmation justifies the premium. Machines outgrowing a single pump can scale into the architectures mapped in the centralized lubrication systems hub.

6. Top Lubrication Pump Brands and Models for CNC Machines

Leading Manufacturers Overview

Premium Tier

Bijur Delimon – Industry leader

• SureFire II Lubricator
• PDI and SLR versions available
• 100+ lubrication points capability
• Price range: $800-$2,000

SKF – Global bearing expertise

• MKF2 series for oil
• P203 series for grease
• Proven reliability
• Price range: $300-$800

Mid-Tier Solutions

DropsA – Italian precision

• Innovative design
• Modular systems
• European quality
• Price range: $400-$1,200

Graco – Industrial solutions

• Robust construction
• Wide application range
• Service network
• Price range: $500-$1,500

Value Tier

IsoHiTech product range:

Hand Oil Lubrication Pump – $25

• Reservoir: 600ml
• Pressure: 1.5MPa
• Outlet: M8 or M10
• Typically used for: Small machines, manual operation

2-4kg Oil Gear Pumps – $150-$200

• Reservoir: 2kg, 3kg, 4kg options
• System: SLR and PDI compatible
• Controller: Optional
• Typically used for: Production CNC centers

System Components:

• Metering unit: $1.0-$1.2 (delivery from slowest to fastest)
• Injector: $3.0-$4.0 (discharge 0.1-0.5ml/cycle)
• Brush: $1.0-$3.0 (delivery from slowest to fastest)

Feature Comparison

Reported Customer Feedback

Reported Feedback Highlights

Reported customer feedback highlights include:

• Competitive pricing
• Direct manufacturer delivery and support
• Clear documentation and installation guidance
• Reliable operation in demanding applications

7. Installation and Maintenance Best Practices

Step-by-Step Installation Guidelines

Pre-Installation Planning

1. System assessment: Identify all lubrication points
2. Pressure calculations: Determine required pump pressure
3. Routing design: Plan distribution lines
4. Electrical requirements: Verify power availability

Installation Process

1. Pump mounting: Secure to vibration-free surface
2. Reservoir filling: Use recommended lubricant grade
3. Line connection: Install distribution tubing
4. Electrical hookup: Connect to CNC control system
5. System testing: Verify operation and adjust settings

Commissioning Checklist

• [ ] All connections leak-free
• [ ] Proper lubricant flow to each point
• [ ] Controller settings verified
• [ ] Safety systems functional
• [ ] Documentation updated

Routine Maintenance Tips

Daily Checks (5 minutes)

• Visual inspection of reservoir level
• Check for leaks at connections
• Verify operation indicator lights
• Listen for unusual pump noises

Weekly Maintenance (15 minutes)

• Clean reservoir sight glass
• Check filter condition
• Inspect tubing for wear or damage
• Test emergency stop functions

Monthly Maintenance (30 minutes)

• Measure lubricant consumption rates
• Replace filters if required
• Calibrate controllers if equipped
• Update maintenance logs

Annual Overhaul (2-4 hours)

• Complete pump disassembly and cleaning
• Replace wear parts (seals, gaskets)
• Pressure test entire system
• Update spare parts inventory

Troubleshooting Common Issues

The following troubleshooting steps apply to common electrical lubrication pump issues.

No Lubrication Output

Troubleshooting steps:

Irregular Lubrication

Recommended actions:

• Check lubricant viscosity: Temperature changes affect flow characteristics
• Inspect metering units: Clean or replace according to the maintenance schedule
• Verify system pressure: Adjust pump settings based on manufacturer specifications
• Examine distribution lines: Clear blocked lines, check for proper routing

Excessive Consumption

Recommended actions:

• Internal seal replacement: Address pump internal leakage
• Pressure calibration: Reduce if system over-pressurized
• Timer optimization: Recalibrate cycle times for efficiency
• Comprehensive leak detection: Repair all connection points

Replacement parts and technical support are available directly from the manufacturer. Payment options include PayPal and TT.

Line Sizing, Priming, and Retrofit Tips for CNC Oil Systems

• Size the main line generously. With ISO VG 68 oil, a 4 mm line loses roughly 2.5 PSI per 10 meters at a 3.2 cc/cycle discharge, while 6 mm tubing loses only about 0.8 PSI — use 6 mm for runs beyond a few meters to stay above the 15 PSI meter-unit minimum.
• Prime patiently. After installation or service, expect 5–10 pump strokes (or several manual-feed cycles) to purge air; start at half-stroke and confirm oil at every point before releasing the machine to production.
• Wire the low-level switch to the control. Connect the float switch to a machine input and configure the alarm logic — running a dry pump destroys it quickly.
• Use the manual feed button after shutdowns. After any stop longer than about 24 hours, trigger an instant cycle to pre-lubricate ways before the first move.
• Keep oil clean and single-grade. Contaminated or mixed oil clogs the 40-micron filter and meter orifices; stick with a quality way oil (ISO VG 68 for slideways) and never introduce grease into an oil system.
• Budget installation time realistically. A manual one-shot retrofit on a knee mill typically takes 2–4 hours with basic mechanical skills; automatic pump retrofits add wiring time for the harness and level switch.

8. Frequently Asked Questions

What is a CNC lubrication system?

A CNC lubrication system is the automatic oil or grease supply that keeps a machine tool’s linear guides, ball screws and spindle bearings lubricated during cutting. Most CNC machines use a small timed cnc lubrication pump (resistance or volumetric type) that meters oil every 15–60 minutes; the selection criteria in this guide — output volume, pressure, discharge interval and alarm feedback — are exactly what keeps a CNC lubrication system trouble-free.

How often should lubrication pumps be serviced?

Short answer: Daily visual checks, weekly basic maintenance, monthly detailed inspection, annual overhaul.

Detailed service schedule:

• Daily: Visual inspection (2 minutes)
• Weekly: Basic maintenance checks (15 minutes)
• Monthly: Detailed inspection (30 minutes)
• Annually: Complete overhaul (2-4 hours)

Can older CNC machines be retrofitted with a new lubrication pump?

Many CNC machines can be retrofitted. Key factors:

• Existing mounting points can often be reused
• Electrical compatibility may require adapters (DC24V recommended)
• Distribution lines might need replacement
• Cost: Typically 20-30% of new system cost

What are the signs of lubrication system failure?

Immediate warning signs:

1. Unusual noises from machine axes (grinding, squealing)
2. Increased power consumption during operation
3. Positioning errors or backlash development
4. Visible wear particles in lubricant (metallic debris)
5. Temperature increases in bearings (+10°C above normal)
6. Empty reservoir with faster-than-normal consumption

Action required: Stop operation and inspect system immediately to prevent major damage.

Which pump is best for oil applications?

Gear pumps like the SKF MKF2 are preferred because they:

• Handle various oil viscosities efficiently
• Provide consistent flow rates
• Operate reliably under pressure
• Require minimal maintenance

How is the choice made between oil and grease lubrication?

Oil lubrication when:

• High-speed operation (>1000 RPM)
• Heat dissipation required
• Automated systems preferred
• Easy pumping needed

Grease lubrication when:

• Low-speed, high-load applications
• Contamination protection required
• Infrequent maintenance desired
• Dripping must be prevented

What’s the ROI of automatic lubrication systems?

Typical payback period: 6-18 months

Reported cost savings in some automatic-lubrication deployments include:

• Reduced downtime: 50-90% improvement reported in some cases
• Extended component life: 200-300% increase reported in some cases
• Lower maintenance costs: 40-60% reduction reported in some cases
• Energy savings: 10-15% improvement reported in some cases

Can IsoHiTech pumps integrate with existing CNC controls?

Yes, IsoHiTech pumps offer multiple integration options:

• Relay contacts for basic on/off control
• Analog signals for variable operation
• Digital interfaces for advanced monitoring
• Custom programming available

What warranty does IsoHiTech provide?

Warranty terms:

• 1 year manufacturer warranty on all pumps
• Technical support included
• Spare parts availability maintained for common models
• Replacement units available for critical applications

People Also Ask

What is a CNC lubrication pump?

A CNC lubrication pump delivers measured oil or grease to critical machine components such as spindle bearings, linear guides, and ball screws. It can operate manually, as an automatic electric unit, or as part of a centralized progressive system. See the lubrication pump classification section.

Why is lubrication important for CNC machines?

Proper lubrication reduces friction and heat at moving surfaces, which helps maintain machining accuracy and extend component life. Inadequate lubrication can contribute to premature wear and increased maintenance costs. The introduction outlines these effects.

What are the main types of CNC lubrication systems?

Common types include manual pumps, automatic electric pumps, and centralized progressive systems. Manual pumps suit small or occasional-use machines; automatic electric pumps fit production CNCs; centralized systems serve large or multi-axis machines. The classification table summarizes the differences.

How is a CNC lubrication pump reservoir sized?

Reservoir size is selected based on the number of lubrication points, lubricant consumption rate, and desired service interval. Small benchtop machines may use 0.5–1 L reservoirs, while large machining centers can require 4 L or more. Reservoir specifications are covered in the pump selection criteria section.

What voltage is commonly used for CNC lubrication pumps?

DC24V is widely used for safety and PLC compatibility; AC220V/230V and AC380V/440V configurations are available for higher-pressure or higher-power applications. Voltage selection should match the machine electrical system and pump power requirements. Details are in the electrical integration section.

Can automatic lubrication improve CNC machine uptime?

Automatic lubrication can reduce manual greasing labor and help avoid missed lubrication cycles, which may lower unplanned downtime in demanding production environments. Reported payback periods are typically 6–18 months, but results vary by application. The classification and conclusion sections discuss these considerations.

What factors affect CNC lubrication pump selection?

Key factors include machine size and complexity, number of lubrication points, lubricant type, voltage compatibility, operating pressure, and integration requirements. Matching these parameters to the pump specification supports reliable performance. The pump selection criteria and technical specifications sections provide guidance.

9. Conclusion

Summary of Key Points

Selecting a suitable CNC lubrication pump for machine applications requires careful consideration of:

1. Machine requirements: Size, complexity, and lubrication points
2. System type: Manual, automatic, or centralized
3. Voltage compatibility: DC24V recommended for safety
4. Lubricant type: Oil for general use, grease for special applications
5. Budget constraints: Balance initial cost with long-term value

Final Recommendations for Buyers

Quick Reference Selection Guide

For Small Workshops

Start with manual pumps ($25-$75)

• Hand oil pumps for occasional use
• Upgrade to automatic when production increases
• Focus on basic reliability

For Production Environments

Invest in automatic electric pumps ($150-$300)

• 2L-4L capacity for most applications
• DC24V for safety and compatibility
• Suitable for value and performance in production environments

For Large Manufacturing

Consider centralized systems ($500+)

• Progressive distribution for complex machines
• Maximum reliability and monitoring
• Professional installation recommended

About IsoHiTech

• Direct manufacturer pricing
• Product range – From $25 hand pumps to $300 industrial systems
• Technical support – Troubleshooting experience with CNC lubrication systems
• Payment options – PayPal and TT accepted
• Volume pricing – Pricing may be negotiated for large quantities
• Direct factory support

Product lineup with listed pricing:

Hand Oil Lubrication Pump – $25

• Reservoir: 600ml
• Pressure: 1.5MPa
• Outlet: M8 or M10

2kg Oil Gear Pump – $150-$200

• Reservoir: 2kg
• System: SLR and PDI compatible
• Controller: Optional

3kg Oil Lubrication Pump – $150-$200

• Reservoir: 3kg
• System: SLR and PDI compatible
• Controller: Optional

4kg Oil Lubrication Pump – $150-$200

• Reservoir: 4kg
• System: SLR and PDI compatible
• Controller: Optional

System Components:

• Metering unit – $1.0-$1.2
  
  Delivery from slowest to fastest
• Injector – $3.0-$4.0
  
  Discharge from 0.1-0.5ml/cycle
• Brush – $1.0-$3.0
  
  Delivery from slowest to fastest

Ordering Information

• Payment Methods: PayPal and TT (Wire Transfer) accepted
• Volume Pricing: Available for large orders
• Timer Systems: Available for automated operation (timer options)

For specifications or volume pricing, contact IsoHiTech.

Frequently Asked Questions

What type of pump is suitable for CNC machines?

Gear pumps are commonly used for small-to-medium CNC mills because they are cost-effective and reliable. Piston pumps are often specified for high-speed machining centers where precise, low-pulsation delivery is preferred. Oil mist systems are typically used for ultra-high-speed spindles (20,000+ RPM).

What pressure should CNC lubrication systems operate at?

CNC lubrication typically operates at 2-8 bar (30-120 PSI), much lower than heavy industrial equipment. Excessive pressure can cause seal damage and oil leaks. Precise pressure control is more important than high pressure.

How is lubrication integrated with a CNC controller?

IsoHiTech pumps offer 24V DC inputs/outputs for PLC integration. Lubrication cycles can be connected to M-codes in the CNC program, or standalone timers with pressure sensors can feed alarm signals to the machine control.

What oil viscosity is recommended for CNC lubrication?

ISO VG 32-68 is standard for most CNC applications. High-speed spindles use VG 10-22 (lower viscosity for better flow). Gearboxes use VG 68-150 (higher viscosity for load carrying). Machine manufacturer specifications should be followed.

How often should CNC lubrication systems run?

Continuous flow for spindles during operation. Intermittent for linear guides (every 15-30 minutes of machine time). Automatic systems run on programmed intervals synchronized with machine cycles, typically via M-code calls.

Can existing CNC machines be upgraded with automatic lubrication?

Yes. Retrofit kits are available for most CNC machines. Installation involves mounting the pump, routing tubing to lubrication points, and connecting to machine power (24V DC or 220V AC). Most retrofits take 4-8 hours per machine.

How is contamination prevented in CNC oil systems?

Use sealed reservoirs with desiccant breathers, 10-micron filtration on inlet and return lines, and regular oil analysis. IsoHiTech systems include filtration and contamination monitoring as standard features.

How many lubrication points can one CNC pump serve?

A typical 3.2 cc cyclic piston pump serves 8–16 points through standard meter units, calculated from pump pressure, discharge volume, and the 15 PSI minimum each meter unit needs. Manual one-shot kits typically cover up to 9 points, while PDI systems scale to 80+ points per pump.

Why is my CNC machine getting a low-lube alarm?

The float switch in the reservoir triggers when roughly 500 ml remains — refill with the correct way oil and the alarm should clear. If the alarm persists with a full reservoir, check the switch wiring and confirm the contact configuration (NO vs. NC) matches the machine control’s input logic.