Modern ammonia sampling techniques using preengineered grab sampling systems can reduce system downtime and improve the bottom line.
Process industry professionals frequently use anhydrous ammonia to manufacture petroleum, fertilisers, textiles, plastics, and more – but it must be used within specific parameters to be safe and effective. It usually contains water, which must fall between 0.2% and 0.5% of the overall substance to prevent it from corroding tubes and pipes, as well as to maintain high product quality in the manufacturing process.
To ensure the water content of ammonia remains in the right range, regular testing is crucial (Figure 1). However, the necessity of such testing does not make it simple because:
- Ammonia is potentially hazardous. An operator must wear the proper personal protective equipment (PPE) since ammonia has the potential to cause significant harm to workers, including burns, eye irritation, and potential death if inhaled. PPE includes goggles, gloves, respirators, and chemical suits.
- It is delicate. Precision is essential in ammonia sampling and testing, and even a small procedural error can lead to inaccuracies that could put workers and product quality at risk.
- It is time-consuming. The entire process of traditional ammonia testing can take up to eight hours, which can slow the production line and reduce overall throughput at a facility.
Figure1. Testing ammonia systems regularly is essential for all process industries to keep employees safe and ensure problems are addressed immediately.
Sampling ammonia manually in an industrial fluid system is a complex process. Once adequately protected, technicians may begin sampling the ammonia, which requires precision and care. Even the smallest mistakes can lead to inaccurate results and render the sample results unusable.
Because manual sampling can negatively affect a facility’s operational efficiency, more efficient and effective options are now available that ensure quality results. By eliminating manual tests and instead using a sampling system specifically designed for testing ammonia, facilities can improve the efficiency, safety, and accuracy of their results.
Figure 2. Glass-enclosed fixtures protect employees from accidental exposure to ammonia, a highly toxic substance.
How Manual Ammonia Sampling Is Done
Technicians commonly perform traditional ammonia sampling using the CGA G-2.2 method, which dispenses a 100 ml sample of liquid ammonia that then evaporates. Technicians measure the residual water to quantify the ammonia’s water content, which should fall between 0.2% and 0.5%. Process operators should take appropriate corrective action if the water content falls outside of those parameters.
Ensuring the water content of anhydrous ammonia is in the ideal range is critical for effective facility operation. Water concentrations lower than 0.2% can lead to ammonia stress corrosion cracking in storage tanks or other fluid system components, which is particularly dangerous because leaks can occur if component alloys weaken.
Stress corrosion weakens components slowly over time, making the possibility of catastrophic, sudden failures more likely. While water content above 0.5% is not dangerous, it is unnecessary.
The CGA G-2.2 method doesn’t always provide accurate measurements. A few variables can compromise accuracy:
- As cold ammonia fills warm glass containers, it immediately begins to boil and evaporate, making it difficult to fill residue tubes to the graduation line
- Inconsistent rates of heating can lead to inconsistency in sample results
- Inadequate flushing of residual water and old samples from the transport line can lead to samples that are not representative
Additionally, the accuracy of manual ammonia sampling depends on the technicians’ level of expertise and steadiness. Filling a warm residue tube requires precision and tests can take up to eight hours before producing results.
The most important aspect, considering anhydrous ammonia’s highly toxic nature, is to keep employees safe. Testing ammonia is a challenging process that demands extensive PPE. This includes wearing goggles, gloves, a respirator, and a chemical suit, because exposure to ammonia vapours could be fatal.
Accidental exposure may lead to prompt irritation of the eyes, nasal passages, throat, and respiratory system, potentially causing blindness, lung impairment, or fatality. Breathing in lesser amounts may induce coughing, as well as irritation of the nose and throat.
Additionally, ammonia escaping into the air poses environmental hazards that could lead to enforcement actions from the Environmental Protection Agency. Always use the right PPE when ammonia sampling and testing occurs and remind employees to avoid releasing ammonia into the environment.
With so many shortcomings, manual sampling is no longer the ideal method of measuring the water content of ammonia. In summary, it requires significant time, as well as high levels of technical skill and precision. Fortunately, sampling technology has evolved so that preengineered systems designed specifically for ammonia can avoid the shortcomings of more traditional manual methods.
Improving Your Process with Preengineered Grab Sampling Systems
Preengineered grab sampling systems are frequently standard equipment at processing facilities. They can be used in nearly any application to improve the safety and reliability of sampling processes.
Installing a system specifically designed for ammonia sampling should minimise technician exposure to liquid and vaporised ammonia and can improve consistency throughout the process.
Ammonia-specific systems should also speed up the sampling process to reduce the overall amount of time invested, particularly when they are installed directly at the sample point.
Figure 4. Capping the residue tube makes it easier for the technician to fill.
Some features to look for may include:
- Closed-sample fixtures. Closed-sample fixtures (Figure 2) can help improve safety by limiting operator exposure and environmental impact. A closed-sample design reduces the need for significant amounts of PPE. Closed fixtures may also be made of glass, allowing the operator to confirm the process is taking place and monitor conditions inside the system without unnecessary exposure to the ammonia.
- Effective chilling mechanisms. Because ammonia boils off quite easily and can threaten fill accuracy, a sampling system designed with effective chilling mechanisms (Figure 3) can help minimise the potential for excessive boiling. Systems with pre-chilled residue tubes are especially effective.
- Semiautomated sample dispensing. A cap assembly can be fitted to the residue tube to assist with the filling process (Figure 4). When dispensing the sample, ammonia fills the residue tube until the level reaches the bottom of the overflow tube. This feature helps ensure consistent sample sizes during each use.
- User-friendly operation. Sampling systems that enable clear and simplified operation can help prevent errors and improve the user experience. For example, a single-handled geared mechanism may enable the technician to operate multiple valves simultaneously, which minimises errors. In addition, some systems may feature an easy touchscreen interface and provide step-by-step operating instructions to control heater operations (Figure 5).
Figure 5. Touchscreen operator interfaces offer ease of use and improved accuracy.
Considering these features is crucial when selecting an ammonia sampling system. To start, find a reliable sampling system equipment supplier. A well-designed system provides better facility safety and can improve the accuracy of the results.
Semiautomating the sampling process means technicians do not need exceptional levels of expertise or experience. Additionally, using preengineered grab sampling systems can make pulling samples easier, thus reducing the amount of time involved.
Particularly in today’s business environment, suppliers should provide raw material traceability throughout their supply chain to make sure the systems arrive as specified. Suppliers should also document that their equipment delivers consistent results.
If uncertainty arises about where to begin, consulting with a reputable component supplier is advisable. Their team can provide guidance in decision-making for constructing an ammonia sampling system and assessing the suitability of a preengineered grab sampling system.
