Category Archive: https://www.ksentry.com/shop/Uncategorized
Across industrial, commercial, and utility sectors, double-wall tanks remain a trusted solution for storing fuels, chemicals, and other regulated liquids. Their dual-wall design provides a critical layer of secondary containment—but the true frontline of protection lies within the interstitial (annular) space between those walls. A breach in the primary tank wall sends product directly into this cavity, creating an early warning opportunity that operators cannot afford to miss. Without reliable monitoring, that first sign of failure can go undetected until structural integrity is compromised and environmental release becomes a real threat.
Krueger Sentry Gauge’s Type K hydrostatic leak detection system gives operators a durable, non-electronic way to continuously indicate interstitial status and catch containment failures early—before damage escalates.
Secondary Containment Integrity: A Regulatory and Financial Priority
In the United States, EPA’s 40 CFR Part 280 requires underground storage tank (UST) systems to implement approved release-detection methods—including interstitial monitoring for secondarily contained systems. Many state and local regulations also apply similar principles to aboveground tanks (ASTs), often referencing codes such as NFPA 30 for safe storage practices. Across all jurisdictions, the message is clear: early detection in the interstitial space is essential for preventing environmental harm and avoiding operational risk.
When a primary wall leaks, product first accumulates within the interstice. If this early signal is ignored, the stored liquid can migrate, attack the secondary wall, or escape through penetrations—potentially resulting in soil or groundwater contamination.
And the financial stakes are real. Cleanup costs for significant releases commonly range from tens of thousands to low six figures, according to EPA-cited corrective-action studies. Add regulatory penalties for non-compliance, and the cost of missing an early interstitial alert quickly becomes substantial.
Your Takeaway: Establish and follow a formal schedule for checking all interstitial monitoring equipment. Many regulatory frameworks for USTs require interstitial monitors to be checked at least every 30 days, and frequent inspection is considered best practice for all double-wall tanks.
The Type K Advantage: Simple, Reliable, Hydrostatic Protection
The Krueger Type K hydrostatic leak detection gauge provides a clean, mechanical approach to monitoring the space between tank walls—no wiring, no electronics, and no power required.
Here’s how it works:
- The annular space is filled with a non-reactive hydrostatic fluid.
- The gauge provides a clear, visual reading of that fluid level.
- If the inner wall leaks, stored product displaces the hydrostatic fluid upward.
- If the outer wall leaks, the hydrostatic fluid drains downward.
This displacement causes an immediate, visible level change on the gauge. When operators incorporate routine visual checks—as required for many regulated UST systems—this method delivers dependable early warning of containment failure.
Why Facilities Choose Hydrostatic Type K Gauges
- Hydrostatic Operating Principle: Direct, mechanical detection with no electronics or power dependence.
- Early Detection Capability: Level changes occur as soon as the interstitial fluid is displaced—allowing fast response when paired with routine inspection or continuous observation.
- Reliable Mechanical Function: Immune to sensor drift, electrical faults, and nuisance shutdowns from power loss.
- Dual-Wall Protection: Registers both primary and secondary wall leaks for comprehensive monitoring.
- Rapid Response Enablement: Clear visual indication supports quick product transfer and maintenance action to minimize loss and contamination risk.
Your Takeaway: Ensure the selected Type K gauge is compatible with both the stored product and tank construction. The hydrostatic fluid must remain stable across your expected temperature and service conditions.
Krueger Sentry Gauge: Confidence Through Mechanical Simplicity
Krueger Sentry Gauge designs Type K hydrostatic leak detectors for real-world industrial service:
- Durable, non-corrosive materials built for long-term exposure
- Highly visible, easy-to-read indicators for fast field assessment
- Low-maintenance operation with no calibration or wiring
- Compatibility with a wide range of double-wall tank configurations
For facilities handling regulated liquids, integrating a Type K gauge into your Asset Integrity Management (AIM) strategy delivers safer operations, clearer compliance pathways, and reduced lifecycle costs.
Your Takeaway: Incorporate visual verification of the Type K gauge into your broader tank inspection routine. Align monitoring frequency with EPA UST requirements, applicable state AST regulations, and codes such as NFPA 30 where adopted.
Contact us today to discuss your needs or request a quote. Our team is ready to help you find the best solutions for your storage systems.
Uncontrolled releases from Aboveground Storage Tanks (ASTs) impose severe financial and environmental penalties on operators. Facility managers must implement robust spill prevention measures to safeguard public safety and maintain operational integrity. A single, catastrophic overfill event can generate millions in cleanup costs and trigger massive federal fines. The reliable Overfill Alert Gauge (Type OF) constitutes a non-negotiable component of any credible spill prevention strategy.
The Mandate for Proactive Level Detection
Regulatory bodies, including the Environmental Protection Agency (EPA), strictly enforce compliance with the Spill Prevention, Control, and Countermeasure (SPCC) rule. This federal mandate requires owners or operators of bulk storage facilities to install reliable warning systems and proper operating procedures. Non-compliance often results in fines reaching tens of thousands of dollars per day, significantly impacting a company’s balance sheet. Industry best practices, specifically outlined in American Petroleum Institute (API) Recommended Practice 2350, further define the accepted protocols for preventing tank overfills in petroleum facilities. This standard dictates that bulk liquid terminal operators should employ a three-tier defense system, mandating reliable high-level alarms to initiate proper emergency response procedures. Facility engineers must determine alarm set points based on tank category, rate of filling, ullage, etc., per API 2350.
- The EPA’s SPCC rule requires all bulk storage facilities exceeding volume thresholds to have reliable overflow prevention.
- API 2350 mandates a multi-tiered defense system, specifying the use of dedicated high-level alarms as a critical safeguard.
- Non-compliance with federal regulations can trigger civil penalties, which vary and can be substantial, alongside mandatory cleanup costs.
- Engineers must set alarm levels aggressively, typically at or below the 98% capacity mark, allowing sufficient time for manual or automatic shutdown.
Your Takeaway: Understand your jurisdictional requirements and establish mandatory alarm set points below the 98% tank capacity level as defined by relevant industry standards and local fire codes.
Decoding the Overfill Alert Gauge (Type OF) Technology
Mechanical float gauges may offer advantages, but the key is an independent detection system as required by API 2350, and the choice of technology must fit the tank, product, risk category, etc. Kreuger Sentry’s Type OF Overfill Alert Gauges offer mechanical simplicity coupled with unparalleled reliability for continuous tank level monitoring. These specialized gauges provide both local indication and remote signaling capabilities, functioning independently of complex electronic tank gauging systems. The gauge utilizes a float mechanism connected to a sensing head, detecting rising fluid levels based on principles of displacement and hydrostatic pressure. Once the fluid surface reaches the pre-determined, critical high-level set point, the float actuates a switch within the gauge head. This activation triggers an immediate, unambiguous warning through a combination of audible and visual alarms, alerting transfer personnel to terminate the loading operation immediately. Complex storage environments demand a multi-tiered defense strategy, integrating the mechanical reliability of a Type OF gauge with other level detection technologies. Engineers ensure maximum safety and compliance by layering safeguards, thereby eliminating the single point of failure inherent in relying on only one monitoring system. The Type OF gauge’s direct mechanical action provides a simple, intrinsically safe means of level detection, making it an optimal final line of defense.
- Type OF gauges operate mechanically, utilizing a float mechanism to detect fluid displacement and rising hydrostatic pressure.
- They function as independent local indication and signaling devices, ensuring reliability even if primary electronic systems fail or lose power.
- Activation at the high-level set point triggers both audible horns and visual beacons, providing immediate, unmistakable warning to operators.
- Their design facilitates integration into a multi-tiered defense system, serving as a robust, non-reliant backup to primary gauging instruments. This is consistent with API 2350’s philosophy of layered protection and independent systems.
Your Takeaway: Implement a multi-tiered defense strategy using distinct, reliable level detection technologies, like the mechanical Type OF gauge, to eliminate single points of failure across your AST inventory.
Achieving Spill Prevention Control and Countermeasure (SPCC) Compliance
Compliance with SPCC means you must have a plan and prevent discharge; the specific instrumentation is usually guided by industry standards (API 2350, NFPA 30) and risk-based decisions.
An adequate Overfill Prevention System (OPS) requires a reliable means of deterring or detecting high-level conditions, typically achieved through automatic shutoff or a high-level alarm. Type OF gauges directly address the alarm component of this regulation, providing the critical, timely notification necessary to prevent an overflow event. Their mechanical design offers an intrinsically safe solution, functioning reliably even when primary power systems fail during a transfer. Tank owners routinely perform thorough inspections and calibration checks on their level detection equipment as a critical operational safeguard. Facility managers must conduct regular physical inspections, ideally on a monthly basis, and calibrate all gauges per the manufacturer’s specifications and the established SPCC plan guidelines. Kruger Sentry produces numerous product options designed to meet various tank sizes and chemical compatibilities, ensuring robust compliance across your entire tank farm.
Explore our available Overfill Alert Gauges to find the system that best protects your assets and satisfies all regulatory requirements:
- Type OF gauges fulfill the SPCC requirement for a high-level alarm, which is a mandatory element of the Overfill Prevention System (OPS).
- The mechanical nature of the gauge offers an intrinsically safe method of detection, ideal for environments storing flammable or combustible liquids.
- Compliance necessitates documented, routine maintenance, including performing physical inspections and calibration checks (e.g., monthly or quarterly).
- Choosing the correct gauge involves considering specific tank geometry, mounting specifications, and the chemical compatibility of the stored product.
Your Takeaway: Conduct regular physical inspections and calibrate all level detection equipment per manufacturer and SPCC plan guidelines to ensure operational accuracy and reliability.
Investing in a robust overfill prevention system is not merely a cost; it represents an essential investment in environmental stewardship and financial resilience. The precise, timely warnings from a Kruger Sentry Type OF gauge enable operators to prevent devastating spills, protecting both the environment and the company’s reputation. Proactive adoption of these systems shields your operation from costly downtime, cleanup expenses, and debilitating regulatory fines. Protect your facility and achieve verifiable AST compliance by specifying a reliable mechanical overfill alert gauge today.
Krueger Sentry is excited to announce our newest product, the KSG Smart Gauge transmitter! This innovative accessory is designed to bring your existing mechanical gauges into the digital age, providing a convenient and cost-effective solution for remote tank monitoring.
How It Works
The KSG Smart Gauge transmitter is a simple, yet powerful, accessory that attaches to your Krueger Sentry mechanical gauge. Once connected, it converts the mechanical reading into a digital output signal (4-20mA), which is an industry-standard. This signal can then be fed into any electronic equipment you have, such as cellular devices, computers, or building management systems.
Keep your eyes on your tank levels without being on site. Imagine being able to check the status of multiple tanks from the comfort of your office or even on your phone!
Affordability and Compatibility
The KSG Smart Gauge transmitter offers a very affordable way to upgrade your system. Instead of replacing all your reliable Krueger Sentry mechanical gauges, you can simply add this accessory to turn them into digital gauges.
It works seamlessly with the following Krueger Sentry gauges:
This accessory-only product is sold separately from the gauges, giving you the flexibility to upgrade your existing setup as needed. The KSG Smart Gauge transmitter is the smart choice for modernizing your tank monitoring capabilities.
See It at NACS Show 2025
Want to see the new KSG Smart Gauge transmitter in person? You can find it at the NACS Show 2025 in two locations:
- Cool New Products Preview Room
- Viewing Booth S3315 in the South Building / Hall A (Level 3)
Stop by and see how this accessory can transform your tank monitoring!
Interstitial monitoring plays a crucial role in tank safety and compliance. This leak detection method guarantees that storage systems adhere to regulatory standards and tank safety requirements. Interstitial monitoring can also protect the environment by controlling leaks and ensuring safe operations in industrial settings.
Delve into what interstitial monitoring is and its role in leak detection and prevention. You’ll also find information on the types of monitoring gauges and systems available at Krueger.
What Is Interstitial Monitoring?
Interstitial monitoring is a leak detection method used in double-walled piping systems. These systems feature an inner and outer pipe with interstitial space between them. Sensors or monitoring devices continuously check for the presence of leaked substances in the area. Piping systems are designed to contain any leaked fuel in the area between the two walls.
The primary goal of interstitial monitoring is to detect leaks earlier so potential issues can be addressed before they become major problems. This proactive approach minimizes the risk of costly clean-ups and environmental damage. Interstitial monitoring is commonly used in underground storage tanks (USTs) and above-ground storage tanks (ASTs), providing a reliable detection method that maintains the integrity of storage systems and protects the environment.
Importance Of Interstitial Monitoring
Interstitial monitoring is a critical component of comprehensive automatic tank gauging systems (ATGS). Federal UST regulations require that the monitoring system in place must reliably detect any leakage coming through the inner wall of the piping system. Interstitial monitoring quickly and consistently detects even the smallest leaks, preventing significant damage and costly repairs.
Monitors can vary in complexity, ranging from simple dipsticks to advanced automated systems:
- Simple Monitors. These monitors are manually checked to detect leaked liquid at the lowest containment point.
- Advanced Systems. More advanced systems can continuously monitor for physical changes or conditions that indicate a potential leak, such as loss of vacuum or changes in monitoring liquid levels.
- Automated Systems. These systems use the latest technology to provide real-time data and alerts, allowing for immediate action and minimizing environmental impact.
Types Of Interstitial Monitoring Gauges & Systems
At Krueger Sentry Gauge, we offer a range of interstitial monitoring gauges and systems designed for reliability and accuracy:
Type K Interstitial Leak Gauge Monitor
Our Type K leak detection gauge is a dependable vertical monitor for double-walled above-ground containment tanks (ASTs). This gauge detects leaks within the annular/interstitial space.
The Type K monitor is ideal for facilities looking for a straightforward, reliable solution to leak detection. Its robust mechanical design promotes durability, dependable monitoring, and easy installation and repairs.
LRDP (Liquid Release Detection Probe)
The LRDP is an advanced, automatic, computer-controlled system for bulk fuel ASTs. It uses a mass-based measurement technique to detect small leaks. The system includes a closed reference tube filled to the same level as the tank, with a differential pressure (DP) sensor to detect any discrepancies.
The LRDP’s sophisticated design offers continuous, accurate monitoring, making it a valuable tool for large-scale fuel storage facilities. This method offers high precision and can be customized to meet your application’s needs. Temperature sensors can also be attached to account for diurnal expansion and contraction with regular testing to minimize the effects of temperature variations.
Interstitial Monitoring Gauges & Systems by Krueger
Investing in interstitial monitoring systems from Krueger Sentry Gauge means prioritizing safety, compliance, and environmental protection. We have been a leading manufacturer of high-quality tank gauges for nearly a century.
Our continued commitment to excellence is evident in the over four million liquid-level gauges we’ve produced, catering to various industries and applications. Our gauges and components are all made in the USA and comply with the Buy American Act.
Contact us today to discuss your needs or request a quote. Our team is ready to help you find the best solutions for your storage systems.
Standard Krueger sight gauges are best known in the petroleum equipment industry for providing inexpensive yet reliable liquid level fill gauges for all types of tanks. Yet with the growing amount of alternative fuels including bio diesel and E-85, we found it advantageous to create sight gauge packages that include all stainless steel or all plastic components. This created an excellent side effect.
Our sight gauges can now handle extremely aggressive chemicals including Sulfuric Acid and Hydrochloric Acid. Some chemical sight gauge examples include:
- All stainless steel chemical fill gauge construction – E-85, Bio Diesel, Peroxide, Nitric Acid, Caustics, Calcium Chloride, KOH, and more.
- All plastic chemical sight gauge construction – Peek Plastic Option – Phosphoric Acid, Hydrochloric Acid, Bleach, and more.
All plastic chemical fill gauge construction – Kynar Plastic Option – Chlorine, Sulfuric Acid, and more.
LED At A Glance Remote Monitor – Liquid Level
The LED At A Glance, a remote display accessory for the Krueger line of liquid level gauges, has been put through some rigorous weather tests and has passed with flying colors.
Early in the winter season, we set up some liquid level gauges outside the shop mounted to some 55 gallon drums. The wires for the remote level monitors were then run over to the wall and the LED At A Glance remote level gauge displays were then set up in exposed areas.
LED At A Glance Remote Monitor – Liquid Level
Luckily, (for our testing purposes anyway), we got hit with a major snow storm. (18 inches of snow, 20 below zero with windchill).
Pictured above (the first picture) you can see the exposed remote display wire encased in ice.
Pictured directly above, you can see how the remote liquid level monitor itself was totally buried in snow and then dug out.
Although we do suggest placing a hood or some other sort protection over the level monitor, in all testing cases the remote liquid level monitor still worked great after the storm went through.
Lee Speakin Geurts
As most of you know, regulations on above ground storage tanks are getting more strict. Krueger Gauge has gotten some third party testing done on our Therma Tank Level Gauge and our Overfill Alert Gauge. The results have gotten us approved by Florida (FDEP) as an overfill prevention device on above ground storage tanks. We have not been informed at this point that we need any special approvals for other states, but you should check with your local governments for info on this. Special Documents are and ordering instructions are required for you to comply with some of these overfill regulations.
- Overfill Gauge Maintenance – PDF File
- Ordering Instructions for Overfill Prevention – PDF File
Also, some time ago, we were approved as a Leak detection gauge on double wall storage tanks in Florida as well. The documents for this are as follows.
- Leak Gauge Recommended Maintenence – PDF File
For more information or product documents, please visit our website.
Lee Geurts
Official Liquid Level Gauge Website -Krueger Gauge
Montana DEQ – Storage Tank Inspection
from Google Alerts – aboveground tank
Is the aboveground storage tank (AST) temporary or permanently removed from … Is the aboveground tank protected from vehicle impacts by posts constructed …
www.deq.mt.gov/pet/Forms/PDFS/StorageTankCkecklist.pdf
PDF is a checklist provided by The Montana DEQ for AST self-inspection.
Krueger Sentry Gauge can provide a high-level overfill alarm (both visual and audible) to notify the person filling the tank that the fluid has reached 90 percent. This should satisfy step eleven on the inspection sheet. See the example products and documents from our website.
The following PDF is the NFPA Code for the above ground storage tank (AST) installation.
Above-Ground-Tank-Installation-Relevant-NFPA-Code
Means shall be provided to prevent overfilling by sounding an alarm when the liquid level in the tank reaches 90 percent of capacity and by automatically stopping the delivery of liquid to the tank when the liquid level in the tank reaches 95 percent of capacity. In no case shall these provisions restrict or interfere with the proper functioning of the normal vent or the emergency vent
Our Overfill alarms, when mounted to our standard liquid level gauge (Therma Gauge), provide a 110 DB alarm to warn that the tank is reaching capacity. The following documents provide testing results and ordering info:
- 90% Overfill Gauge Ordering
- Intrinsically Safe Documentation on the gauge alarm
- Recommended Maintenance and Installation Procedure on liquid level tank gauges
In cases where liquids are flammable and fire protection is paramount, adding the Glass Calibration and the Aluminum Lock Nut to the gauge should eliminate the plastic from the gauge and provide a glass and metal barrier between the inside of the tank and the outside. For additional protection, upgrade the Aluminum Nut to the Gauge Guard.
Already have a Krueger Gauge and want to get it up to code. If the gauge is fully functional, just order our upgraded Fire Protection Gauge Repair Kit and an overfill alarm. In the case of the kit, we will need to know what gauge type you have. Example part number is (-”gauge type”-Kit-GLC-ALN). Both the kit and the alarm are easily retrofitted to existing Krueger Tank Gauges.
Vermont’s Above Ground Storage Tank Rules
What is required for new tank installations?
All new tank installations must have….
https://www.vermontfuel.com/ASTfaqs_files/VTsabovegroundstoragetankregs.pdf
Krueger Sentry Gauge can fill the needs for the a vent alarm or “whistle” that terminates near the fill pipe and the gauging device.
Our most versatile liquid level site gauge is the Type H Therma Gauge
Add our Remote Audible Whistle Alarm to the gauge and you are good to go.
https://www.ksentry.com/ralarm.htm
