Online tuning fork density meter · PS7400

Ethylene Glycol EG / Propylene Glycol PG Online Concentration Monitoring – Dual Optimization for Freeze Protection and Heat Transfer

Data center liquid cooling circulation

In AI liquid-cooled data centers, long-term drift in the concentration of the ethylene glycol coolant has led to freezing and tube ruptures in dry coolers during winter, as well as reduced heat-transfer efficiency. The PS7400 online tuning fork concentration meter is directly installed in the primary circulation loop; leveraging its factory‑preset EG/PG concentration curve and PT1000 temperature compensation, it delivers sub‑second continuous monitoring with a concentration accuracy of ±0.5 vol%, enabling precise concentration control and reducing pump energy consumption by 6%.

Applicable industries
Data Center / HVAC Liquid Cooling
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Ethylene Glycol EG / Propylene Glycol PG Online Concentration Monitoring – Dual Optimization for Freeze Protection and Heat Transfer

PISONICS· Xi’an Pisonics

PS7400 Series

Online Tuning Fork Density/Concentration Meter

Piezoelectric Excitation · Tuning Fork Resonance · Plug-and-Play · Maintenance-Free

Data Center / HVAC Ethylene Glycol Chilled Fluid Industry Application Case

—— Online Monitoring of Ethylene Glycol EG/Propylene Glycol PG Concentration · Dual Optimization for Freeze Protection and Heat Transfer ——

A New Essential Requirement for AI Liquid-Cooled Data Centers · Real-Time Tracking of Concentration Drift · Zero Loss from Pipe Ruptures

【Key Measured Parameter: Ethylene Glycol EG/Propylene Glycol PG Concentration (% by vol)】

Data Center/HVAC Ethylene Glycol Chilled Fluid · PS7400 Tuning Fork Density Meter Application Solution

1. Process Background

With the explosive growth of AI computing power driven by ChatGPT and large-scale models, the power per server cabinet has surged from the traditional 5–15 kW to 50–150 kW. Conventional air cooling can no longer meet the cooling demands, and **liquid-cooled data centers** (cold-plate, immersion, or in-row air-conditioning systems) have become the mainstream choice for newly built hyperscale data centers. Liquid-cooling systems employ a closed-loop architecture: server cabinets → CDU cold plates or immersion tanks → hot return water → outdoor water-cooled or air-cooled chillers/dry coolers → chilled supply water → cabinets. The circulating medium is typically an aqueous solution of ethylene glycol (EG, usually 30–50 vol%) or propylene glycol (PG, more environmentally friendly).

The concentration of ethylene glycol (typically 30–50 vol%) ensures both freeze protection and efficient heat transfer: too low a concentration risks freezing and bursting of outdoor dry coolers in northern winters, with rupture losses reaching several million yuan; too high a concentration increases viscosity, reduces the heat-transfer coefficient, and raises circulating-pump energy consumption by 5%–10%. Over long-term operation, the concentration gradually drifts (due to water evaporation, slow oxidative degradation of ethylene glycol, and operator dosing errors), accumulating a shift of 5%–10% over 3–5 years. Traditional manual sampling combined with a refractometer once a month is far from sufficient. In addition to data centers, this solution also applies to metro ventilation cooling stations, commercial complex cooling plants, chemical process cooling, ice storage cooling, and other HVAC applications.

2. Pain Points of Conventional Density/Concentration Measurement Solutions

• Too low ethylene glycol concentration → Winter freezing and bursting of outdoor dry coolers, with single-incident losses amounting to millions of yuan (equipment damage + server downtime and SLA breaches);

• Too high concentration → Increased viscosity, reduced heat-transfer efficiency, and a 5%–10% rise in circulating-pump energy consumption, adding hundreds of thousands of yuan to annual electricity costs;

• The root causes of prolonged drift—water evaporation (from open补水), slow oxidative degradation of ethylene glycol, and operator dosing deviations—accumulate to 5%–10% over 3–5 years;

• Traditional manual sampling and monthly refractometer checks are woefully inadequate for tracking continuous drift, and IDC facility operators often lack familiarity with chemical analysis.

3. PS7400 Solution

The PS7400 is installed via a flanged F1 bracket directly into the main chilled-water return line of the data-center liquid-cooling loop (typically DN50–DN100), continuously monitoring the concentrations of ethylene glycol and propylene glycol. The instrument calls up proprietary EG/PG concentration curves based on factory‑selected codes (B = hydrochloric acid / C = sulfuric acid / D = ammonia / E = alcohol; ethylene glycol/propylene glycol can be designated as X for special custom orders), requiring no on-site modeling and enabling plug‑and‑play operation.

Figure 1: Data Center/HVAC Ethylene Glycol Chilled Fluid Concentration Monitoring Solution

Core Technical Value of the PS7400 in Data Center/HVAC Ethylene Glycol Chilled Fluid Applications

▶ The PS7400 achieves an accuracy of ±0.001 g/cm³—corresponding to an ethylene glycol concentration accuracy of ±0.5 vol%, sufficient to support data center operations and maintenance decision-making;

▶ It comes pre‑configured with factory‑installed EG/PG concentration curves—matching Emerson Micro Motion FDM’s “density + PT1000 temperature → direct concentration readout” capability, eliminating the need for on‑site modeling;

▶ PT1000 automatic temperature compensation—covering the entire operating temperature range of 5–45°C for data center chilled fluids, delivering true “standard‑state concentration”;

▶ DN50/DN100 flange‑mounted direct insertion—installed on the main circulation return pipeline at bracket F1, requiring no maintenance for ≥5 years;

▶ 4–20 mA + Modbus connectivity to BMS/iDCIM systems—enabling intelligent data center operations and remote real‑time cloud‑based monitoring;

▶ Also applicable to HVAC scenarios—metro ventilation chillers, commercial complex chillers, chemical cooling, ice storage cooling, and more.

4. Customer Value

Comparison Dimensions

Original Manual Sampling Scheme

PS7400 Online Solution

Sampling frequency

Once per month

second-level continuous

Drift Identification

Passive detection after the fact

Real-time tracking

Tube Burst Accident

Risks persist

Risk is significantly reduced

Viscosity Optimization

Replenish fluid based on experience

Precision concentration control · Reduces pump energy consumption by 5–10%

Operational and Maintenance Burden

Dependent on chemical analysts

Maintenance-free · Cloud-based data

BMS Integration

Local instrument · Offline

Direct Modbus integration

In the new construction of a certain domestic hyperscale AI data center (with a total campus power of 200 MW and over 5,000 liquid-cooled server cabinets), twelve PS7400 units were deployed across the main chilled-water return lines, forming a campus‑level real‑time ethylene glycol concentration monitoring network. After one year of operation, the system increased concentration‑drift detection from the original once‑monthly to continuous at the second level, and no winter freezing‑related pipe ruptures occurred across the entire campus. Annual aggregate energy consumption of the circulating pumps decreased by approximately 6% (equivalent to savings of several million yuan in electricity costs). This solution has become the standard configuration for the client’s subsequent large‑scale liquid‑cooled data‑center projects and has been extended to multiple city metro ventilation cooling stations.

Conclusion

Based on the PS7 series’ diverse density/concentration measurement principles (acoustic impedance PS7000, sound‑velocity method PS7020, spectroscopy PS7100, and tuning‑fork method PS7400), Xi’an Pisonics (PISONICS) has developed a comprehensive industrial‑process instrumentation portfolio, covering everything from solid‑containing two‑phase slurries to clean, homogeneous liquids, from single‑component to multi‑component media, and from cost‑effective to high‑precision models. Among these, the PS7400 tuning‑fork density meter—grounded in the mature physical principle of piezoelectric excitation and resonant‑frequency detection, benchmarked against international mainstream brands such as Emerson Micro Motion FDM and E+H Liquiphant—is an “plug‑and‑play, maintenance‑free” economical choice for measuring the density/concentration of clean to slightly contaminated liquids.

Tailored to the process characteristics of the data‑center/HVAC ethylene glycol chilled‑fluid sector, the PS7400 online tuning‑fork density/concentration meter offers full‑dimensional selection and customization options, including wetted‑part materials (316L, Hastelloy, titanium, zirconium, PTFE), surface finishes (standard polishing, electrolytic polishing, PTFE coating), process connections (flange, clamp, threaded), mounting accessories (F0–F6), explosion‑proof ratings, and communication protocols (4–20 mA, HART, RS485). For an in‑depth discussion of your project’s specific operating conditions or to obtain a tailored selection proposal, please feel free to contact the Xi’an Pisonics technical engineering team at any time.

More applications for Online tuning fork density meter

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Online detection on the multi-product batch interface

When a long-distance refined‑oil pipeline sequentially transports multiple batches of gasoline, jet fuel, diesel, and other products, the interface mixing zone is difficult to identify accurately, resulting in substantial volumes of substandard oil being sent back for reprocessing and annual losses amounting to several million yuan. The PS7400 online tuning‑fork concentration meter tracks process density changes with second‑level precision at ±0.001 g/cm³, coupled with temperature compensation and an explosion‑proof design, to trigger downstream cut‑off valves in real time, reducing the length of the mixing zone by 30% to 50%. It completely replaces the nuclear density meter while eliminating the burden of radiation management.

LPG / Liquefied Petroleum Gas Trade Handover

In LPG trade handover, the conventional table‑lookup estimation method and manual sampling result in density measurement errors exceeding 0.5%, leading to commodity‑value discrepancies of hundreds of thousands of yuan for ten‑thousand‑ton‑level loading and unloading operations. The PS7400 explosion‑proof online tuning fork concentration meter is directly installed on the main pipeline for loading onto tank trucks or ships, delivering real‑time process‑condition density within seconds. When paired with a volumetric flowmeter and a flow computer, it enables real‑time mass settlement in compliance with the OIML R117 standard.

37 wt% dilute sulfuric acid feed tank concentration fine control · PTFE-coated ultrasonic tuning fork resistant to acid

In the electrolyte-filling section of lead-acid battery production, the 37 wt% dilute sulfuric acid mixing tank has long relied on manual sampling with a density bottle, resulting in large concentration fluctuations and delayed response, which in turn leads to poor consistency in battery capacity. The PS7400 PTFE-coated tuning fork concentration meter is directly installed on the tank’s side wall, providing density readings and converting them to wt% within seconds, and, when integrated with the DCS, enables closed-loop control of concentrated sulfuric acid and deionized water. As a result, concentration variations have been reduced from ±0.6 wt% to within ±0.08 wt%.

Online Concentration Monitoring of 32% / 48% NaOH Storage Tanks

In the concentration monitoring of 32% and 48% NaOH storage tanks, the customer faced challenges such as delays in manual sampling, short instrument lifetimes due to corrosion by high-temperature strong alkali, control lag in the evaporation section, and significant discrepancies in trade settlement. The PS7400 online tuning fork concentration meter, with wetted parts made of 316L and Hastelloy, delivers a concentration accuracy of ±0.1 wt%, operates reliably at temperatures up to 65°C, and reduces on‑truck verification time to within 5 minutes, thereby enabling DCS‑based closed‑loop energy savings and precise settlement of cargo payments on a 100‑ton basis.