Added a binary version and fixed up sprites

code/game/objects/items/RPD.dm

@@ -19,6 +19,7 @@ GLOBAL_LIST_INIT(atmos_pipe_recipes, list(
 		new /datum/pipe_info/pipe("Manifold",			/obj/machinery/atmospherics/pipe/manifold),
 		new /datum/pipe_info/pipe("Manual Valve",		/obj/machinery/atmospherics/components/binary/valve),
 		new /datum/pipe_info/pipe("Digital Valve",		/obj/machinery/atmospherics/components/binary/valve/digital),
+		new /datum/pipe_info/pipe("Relief Valve",		/obj/machinery/atmospherics/components/binary/relief_valve),
 		new /datum/pipe_info/pipe("4-Way Manifold",		/obj/machinery/atmospherics/pipe/manifold4w),
 		new /datum/pipe_info/pipe("Layer Manifold",		/obj/machinery/atmospherics/pipe/layer_manifold),
 	),

code/modules/atmospherics/machinery/components/binary_devices/relief_valve.dm

@@ -0,0 +1,108 @@
+/obj/machinery/atmospherics/components/binary/relief_valve
+	name = "binary pressure relief valve"
+	desc = "Like a manual valve, but opens at a certain pressure rather than being toggleable."
+	icon = 'icons/obj/atmospherics/components/relief_valve.dmi'
+	icon_state = "relief_valve-t-map"
+	can_unwrench = TRUE
+	construction_type = /obj/item/pipe/binary
+	var/opened = FALSE
+	var/open_pressure = ONE_ATMOSPHERE * 3
+	var/close_pressure = ONE_ATMOSPHERE
+	pipe_state = "relief_valve-t"
+
+/obj/machinery/atmospherics/components/binary/relief_valve/layer1
+	piping_layer = PIPING_LAYER_MIN
+	pixel_x = -PIPING_LAYER_P_X
+	pixel_y = -PIPING_LAYER_P_Y
+
+/obj/machinery/atmospherics/components/binary/relief_valve/layer3
+	piping_layer = PIPING_LAYER_MAX
+	pixel_x = PIPING_LAYER_P_X
+	pixel_y = PIPING_LAYER_P_Y
+
+/obj/machinery/atmospherics/components/binary/relief_valve/update_icon_nopipes()
+	if(dir==SOUTH)
+		setDir(NORTH)
+	else if(dir==WEST)
+		setDir(EAST)
+	cut_overlays()
+
+	if(!nodes[1] || !opened || !is_operational())
+		icon_state = "relief_valve-t"
+		return
+
+	icon_state = "relief_valve-t-blown"
+
+/obj/machinery/atmospherics/components/binary/relief_valve/proc/open()
+	opened = TRUE
+	update_icon_nopipes()
+	update_parents()
+	var/datum/pipeline/parent1 = parents[1]
+	parent1.reconcile_air()
+
+/obj/machinery/atmospherics/components/binary/relief_valve/proc/close()
+	opened = FALSE
+	update_icon_nopipes()
+
+/obj/machinery/atmospherics/components/binary/relief_valve/process_atmos()
+	..()
+
+	if(!is_operational())
+		return
+
+	var/datum/gas_mixture/air_contents = airs[1]
+	var/our_pressure = air_contents.return_pressure()
+	if(opened && our_pressure < close_pressure)
+		close()
+	else if(!opened && our_pressure >= open_pressure)
+		open()
+
+/obj/machinery/atmospherics/components/binary/relief_valve/ui_interact(mob/user, ui_key = "main", datum/tgui/ui = null, force_open = FALSE, \
+																datum/tgui/master_ui = null, datum/ui_state/state = GLOB.default_state)
+	ui = SStgui.try_update_ui(user, src, ui_key, ui, force_open)
+	if(!ui)
+		ui = new(user, src, ui_key, "atmos_relief", name, 335, 115, master_ui, state)
+		ui.open()
+
+/obj/machinery/atmospherics/components/binary/relief_valve/ui_data()
+	var/data = list()
+	data["open_pressure"] = round(open_pressure)
+	data["close_pressure"] = round(close_pressure)
+	data["max_pressure"] = round(MAX_OUTPUT_PRESSURE)
+	return data
+
+/obj/machinery/atmospherics/components/binary/relief_valve/ui_act(action, params)
+	if(..())
+		return
+	switch(action)
+		if("open_pressure")
+			var/pressure = params["open_pressure"]
+			if(pressure == "max")
+				pressure = MAX_OUTPUT_PRESSURE
+				. = TRUE
+			else if(pressure == "input")
+				pressure = input("New output pressure (0-[MAX_OUTPUT_PRESSURE] kPa):", name, open_pressure) as num|null
+				if(!isnull(pressure) && !..())
+					. = TRUE
+			else if(text2num(pressure) != null)
+				pressure = text2num(pressure)
+				. = TRUE
+			if(.)
+				open_pressure = CLAMP(pressure, 0, MAX_OUTPUT_PRESSURE)
+				investigate_log("open pressure was set to [open_pressure] kPa by [key_name(usr)]", INVESTIGATE_ATMOS)
+		if("close_pressure")
+			var/pressure = params["close_pressure"]
+			if(pressure == "max")
+				pressure = MAX_OUTPUT_PRESSURE
+				. = TRUE
+			else if(pressure == "input")
+				pressure = input("New output pressure (0-[MAX_OUTPUT_PRESSURE] kPa):", name, close_pressure) as num|null
+				if(!isnull(pressure) && !..())
+					. = TRUE
+			else if(text2num(pressure) != null)
+				pressure = text2num(pressure)
+				. = TRUE
+			if(.)
+				close_pressure = CLAMP(pressure, 0, MAX_OUTPUT_PRESSURE)
+				investigate_log("close pressure was set to [close_pressure] kPa by [key_name(usr)]", INVESTIGATE_ATMOS)
+	update_icon()

code/modules/atmospherics/machinery/components/unary_devices/relief_valve.dm

@@ -2,7 +2,7 @@
 	name = "pressure relief valve"
 	desc = "A valve that opens to the air at a certain pressure, then closes once it goes below another."
 	icon = 'icons/obj/atmospherics/components/relief_valve.dmi'
-	icon_state = "relief_valve-e"
+	icon_state = "relief_valve-e-map"
 	can_unwrench = TRUE
 	var/opened = FALSE
 	var/open_pressure = ONE_ATMOSPHERE * 3

code/modules/atmospherics/machinery/datum_pipeline.dm

@@ -227,6 +227,11 @@
 				if(V.on)
 					PL |= V.parents[1]
 					PL |= V.parents[2]
+			else if (istype(atmosmch,/obj/machinery/atmospherics/components/binary/relief_valve))
+				var/obj/machinery/atmospherics/components/binary/relief_valve/V = atmosmch
+				if(V.opened)
+					PL |= V.parents[1]
+					PL |= V.parents[2]
 			else if (istype(atmosmch, /obj/machinery/atmospherics/components/unary/portables_connector))
 				var/obj/machinery/atmospherics/components/unary/portables_connector/C = atmosmch
 				if(C.connected_device)