Electromagnetic gas valve coil (solved) - Page 1
Forum section: electronics / general

author: antenna
author_rank: Frequent Contributor
timestamp: December 29, 2024, 01:23:59 am
content: EDIT: it only draws 14w. Not the 84w I thought it would be, so im not worried. thanks!I bought an electric valve for a convenient way to turn off the propane gas to the kitchen range. I plan on installing it on the low pressure side of the regulator. We have an energetic cat, and a wood stove, and I don't want to come home to a crater from him turning the burner on. The coil is the reason for the post. I figured being able to flip a switch only when we use it was a good solution to my worries.The valve:https://www.amazon.com/dp/B083ZL8WRG?ref=ppx_yo2ov_dt_b_fed_asin_titleClaims:110v-120v0.2A or 24wNot to run it more than 8 hours.My ohm meter says 143.2, so that's more like 84w, right?I assume that 8 hour limit is because 84w would have melted the plastic by then. Maybe that is just how much power is needed to open it at the rated 145psi, but I only need it to open at about 4psi. Should I use a variac to see what the minimum voltage is to reliably open the valve and go with that? I dont want to worry about the coil if I forget the switch on.

author: johansen
author_rank: Super Contributor
timestamp: December 29, 2024, 05:55:12 pm
content: Doesnt really look like a ul listed gas valve

author: Zero999
author_rank: Super Contributor
timestamp: December 29, 2024, 09:00:40 pm
content: The resistance will be lower than the power consumption would indicate because of the inductance.It still doesn't add up though:If the power drawn is 14W and the resistance is 143R, calculate the current:P = I2RRearrange for II2= P/RI = √(P/R)I = √(14/143) = 0.31AWhich is much less than the 0.2A specified.The specification must be wrong.

author: johansen
author_rank: Super Contributor
timestamp: December 29, 2024, 10:04:55 pm
content: Losses in the eddy currents ..

author: Zero999
author_rank: Super Contributor
timestamp: December 29, 2024, 10:31:58 pm
content: Quote from: johansen on December 29, 2024, 10:04:55 pmThat would appear as another resistor in parallel, so it wouldn't account for the discrepancy in the calculations and the difference wouldn't be so great.

author: NiHaoMike
author_rank: Super Contributor
timestamp: December 29, 2024, 11:12:42 pm
content: Given the cost of propane nowadays, have you considered switching to induction?

author: antenna
author_rank: Frequent Contributor
timestamp: December 30, 2024, 04:08:20 am
content: The power meter said 14w with a current draw of 0.15A and a PF of .75. I assume the listed 0.2A might be the pulling current and not the holding current. The reactance will limit the power consumed by the coil, so its not just the 143 ohms as I thought.I am not worried about whether or not the valve is UL listed. It will be on the low pressure side, and if it fails to seal internally, I am simply back to where I am now, hoping the cat don't turn the range knobs on when I forget to turn it off at the tank (he never has, but I worry). The valve will also be installed outside in a weatherproof vented enclosure, so if the seal does go bad to the atmosphere, it will leak outside where I will smell it. In any event, I will notice if the valve fails before it ever becomes a danger.When I initially posted, I wasn't considering inductance or the valve moving. Most of my interests are in HF, so when I think of 60Hz, i default to thinking resistance only. I know reactance is an issue at mains frequency, I just had my stupid hat on.

author: antenna
author_rank: Frequent Contributor
timestamp: December 30, 2024, 04:24:35 am
content: Quote from: NiHaoMike on December 29, 2024, 11:12:42 pmWe live in an area where the power can go out and stay out for a while. Most people think the US power grid is flawless, but I am in a remote area, and when big storms go through, we are at the end of our little coop's list. We have a generator for the freezers, but it wouldn't handle a full cook top and oven. Besides, I have used both electric and gas for cooking many times in my life and there really is no comparison, gas wins every time. Personal preference I guess. As long as I can lift a 100lb tank in the truck, I will use propane for cooking.

author: NiHaoMike
author_rank: Super Contributor
timestamp: December 30, 2024, 01:02:56 pm
content: Consider getting an induction cooker or two to use as the primary and keep the propane for backup.

author: Zero999
author_rank: Super Contributor
timestamp: December 30, 2024, 04:35:23 pm
content: Quote from: antenna on December 30, 2024, 04:08:20 amOr just rounded up.Your measurements could also be off, because the meter might not be designed for such light loads.

author: antenna
author_rank: Frequent Contributor
timestamp: December 31, 2024, 02:51:40 am
content: I used a P3 International "Kill A Watt" meter the power company gave out to all their customers. I don't plan to leave the valve on for very long, only when cooking, so I doubt it will overheat. If it burns up, I'll just go buy an ASCO RedHat valve (like I should have, I was being cheap).

author: Zero999
author_rank: Super Contributor
timestamp: December 31, 2024, 05:04:00 pm
content: Quote from: antenna on December 31, 2024, 02:51:40 amRounding might partly explain it. Your meter has a full range of 15A and the current is1/100of that.

author: antenna
author_rank: Frequent Contributor
timestamp: January 01, 2025, 12:05:54 am
content: I will test it again with a different current meter and see if the numbers match. At work now.