Why today they might not be the optimal choice for your application.
By Gregg Schneider, Vice President, Gateway Products Group, Inc.
Industrial spark plugs designed with precious metals, such as Platinum, Iridium and then Rhodium alloys, were developed to increase performance (life between PM’s). Though life varies from application to application, and is impacted by gas quality, spark plug designs generally fall into the following categories:
- J Gap Non-Precious Metal: (Shortest Life) 500+ hours
- Multi-Ground Non-Precious Metal: (Longer Life) 500 – 1000+ hours
- Platinum: (Life similar to Multi Ground) 1000 – 1500 hours
- Iridium: (Extended Life) 1500 – 4000 hours
- Multi-Ground Iridium/Rhodium Alloys: (Longest Life) 4000 – 8000 hours
In untreated gas applications, such as Landfill, Ag, and other Digester Operations, the life of precious metal industrial spark plugs is typically shorter than similar applications that use high BTU fuel with minimal contaminants. Therefore, it is important to consider the specifications of your application, and the changing landscape of precious metal industrial spark plugs, when selecting the optimal plugs for your stationary engine.
Taking an increasing share of operational costs
Industrial spark plugs are consumables, replaced at regularly scheduled PM cycles to maximize performance and output. As a result, for stationary engines, they consistently rank in the top five from an operational cost standpoint, generally behind oil and filters. Recently, you might have seen your spark plugs’ share of operational costs grow. This can be attributed to several reasons:
- Cost of materials: Many of you may have noticed price increases on Iridium and Iridium/Rhodium spark plug designs. These increases represent cost that manufacturers need to pass along in order to offset material pricing. For example:
| Precious Metal | January 2019 | May 2021 |
|---|---|---|
| Iridium | $1,480 USD per ounce | $6,300 USD per ounce |
| Rhodium | $2,640 ISD per ounce | $29,000+ USD per ounce |
As a result, when using plugs with these precious metals, runtime per hour costs will increase, as cost increases but operating hours remain constant.
- Supply Logistics: For non-precious metal plugs, material sources are more plentiful, with a wider competitive base of suppliers. As a result, commodity market prices are more stable compared to exotic metals. Increasing logistical costs, from mining operations, freight, and labor, impact both precious metal and non-precious metal products in similar fashions and force future price adjustments in an equal way for all spark plugs. Most manufactures did not take significant price increases on non-precious metal plugs, widening the spread in acquisition costs between the two designs. We will address a hypothetical situation on a landfill gas application in the next section.
Cost analysis: More frequent PMs vs long-life plugs
Because of the dramatic increases in the cost of precious metals, runtimes per hour may now favor more frequent PM’s than running higher-cost, long-life plugs. Consider this sample scenario for a hypothetical untreated fuel landfill power generation site:
| Design | Total Operating Hours | Price (hypothetical) | Cost per operating hr. (without labor)* | Annual cost (8,000 hrs.) 16 cyl engine | Annual cost (8,000 hrs.) 20 cyl engine |
|---|---|---|---|---|---|
| Iridium | 2,000 | $80 | .04 | $5,120 | $6,400 |
| 4-prong Nickel | 500 | $18 | .036 | $4,608 | $5,760 |
| Total Savings (per engine/ per year) | $ 512 | $ 640 |
*Since there are various PM timeframes for precious metal industrial plugs, typically around 700 hours in landfill applications, we have not estimated additional labor costs for cleaning and re-gapping as part of our cost review. In addition, we have not calculated the additional number of PM’s required to use non-precious metal plugs, as it will vary by site. Each location would need to consider this as part of a review for a true picture of potential savings and every location will have a different outcome.
Though top-of-the-line precious metal industrial plugs generally offer the advantage of the longest run time per hour, given the changing metals markets, now may be a time to review best operational practices. GPG is here to assist. We supply all ranges of plugs in multiple brands to maximize your profitability. Please feel free to call me, Gregg Schneider, at 314-324-3096, to discuss your situation and if an alternative might be right for your operation.