diff --git a/basic_machines/concentrator.lua b/basic_machines/concentrator.lua
index 2d5217c..eed6f43 100644
--- a/basic_machines/concentrator.lua
+++ b/basic_machines/concentrator.lua
@@ -62,7 +62,7 @@ local names = networks.register_junction("techage:concentrator", 2/8, Boxes, Tub
 techage.register_node(names, {
 	on_push_item = function(pos, in_dir, stack)
 		local push_dir = M(pos):get_int("push_dir")
-		return techage.push_items(pos, push_dir, stack)
+		return techage.safe_push_items(pos, push_dir, stack)
 	end,
 	is_pusher = true,  -- is a pulling/pushing node
 })	
@@ -101,7 +101,7 @@ names = networks.register_junction("techage:ta4_concentrator", 2/8, Boxes, Tube,
 techage.register_node(names, {
 	on_push_item = function(pos, in_dir, stack)
 		local push_dir = M(pos):get_int("push_dir")
-		return techage.push_items(pos, push_dir, stack)
+		return techage.safe_push_items(pos, push_dir, stack)
 	end,
 	is_pusher = true,  -- is a pulling/pushing node
 })	
diff --git a/basis/command.lua b/basis/command.lua
index 435818b..301cf3b 100644
--- a/basis/command.lua
+++ b/basis/command.lua
@@ -405,6 +405,31 @@ function techage.push_items(pos, out_dir, stack, idx)
 	return false
 end
 
+-- Check for recursion and too long distances
+local start_pos
+function techage.safe_push_items(pos, out_dir, stack, idx)
+	local mem = techage.get_mem(pos)
+	if not mem.pushing then
+		if not start_pos then
+			start_pos = pos
+			mem.pushing = true
+			local res = techage.push_items(pos, out_dir, stack, idx)
+			mem.pushing = nil
+			start_pos = nil
+			return res
+		else
+			local npos, in_dir, name = get_dest_node(pos, out_dir)
+			if vector.distance(start_pos, npos) < (Tube.max_tube_length or 100) then
+				mem.pushing = true
+				local res = techage.push_items(pos, out_dir, stack, idx)
+				mem.pushing = nil
+				return res
+			end
+		end
+	end
+	return false
+end
+
 function techage.unpull_items(pos, out_dir, stack)
 	local npos, in_dir, name = get_dest_node(pos, out_dir)
 	if npos and NodeDef[name] and NodeDef[name].on_unpull_item then
diff --git a/logic/node_detector.lua b/logic/node_detector.lua
index deb1d26..eed6d7f 100644
--- a/logic/node_detector.lua
+++ b/logic/node_detector.lua
@@ -60,20 +60,21 @@ local function any_node_changed(pos)
 		nvm.num = #minetest.find_nodes_in_area(nvm.pos1, nvm.pos2, {"air"})
 		return false
 	end
-	local num = #minetest.find_nodes_in_area(nvm.pos1, nvm.pos2, {"air"})
+	local num1 = #minetest.find_nodes_in_area(nvm.pos1, nvm.pos2, {"air"})
+	local num2 = #minetest.find_nodes_in_area(nvm.pos1, nvm.pos2, {"ignore"})
 	
-	if nvm.num ~= num then
-		if nvm.mode == 1 and num < nvm.num then 
-			nvm.num = num
+	if num2 == 0 and nvm.num ~= num1 then
+		if nvm.mode == 1 and num1 < nvm.num then 
+			nvm.num = num1
 			return true
-		elseif nvm.mode == 2 and num > nvm.num then 
-			nvm.num = num
+		elseif nvm.mode == 2 and num1 > nvm.num then 
+			nvm.num = num1
 			return true
 		elseif nvm.mode == 3 then
-			nvm.num = num
+			nvm.num = num1
 			return true
 		end
-		nvm.num = num
+		nvm.num = num1
 	end
 	return false
 end